Gearbox of saddle-ridden vehicle

ABSTRACT

A gearbox includes a transmission mechanism and a clutch system including plural clutches. The gearbox has a gear change mechanism that is interlocked with a change pedal shaft to which rotational force by operation of a shift pedal is transmitted and arbitrarily selects a transmission gear of the transmission mechanism to perform gear shift. An ECU can electronically control connection/disconnection of the clutch system according to a shift position of the gear change mechanism.

BACKGROUND

1. Field

The present invention relates to a gearbox of a saddle-ridden vehicle.

2. Description of the Related Art

As a gearbox of a saddle-ridden vehicle, there is a gearbox in which acontrol measure that has detected an indication of intention of gearshift from a gear selector operation based on manual operation by adriver causes electromagnetic actuation of a clutch actuator todisconnect a clutch and electrically drives a motor that shifts a changedrum to perform gear shift to the selected shift stage, such aconfiguration is shown, for example, in Patent Document 1 (JapanesePatent Laid-Open No. 5-157163).

However, in such an electrically-driven gearbox, the clutch actuationtime and the gear shift operation time depend greatly on the performanceof the actuator and the motor. Therefore, depending on the performanceof them, when shift operation is carried out in vehicle driving, theclutch connection/disconnection time is long and the time until thecompletion of gear shift actuation is long, so that interruption of thedriving force occurs. In addition, the driver is often made to feel thatthe time until gear shift completion is longer compared with a manualoperation vehicle.

In particular, for the saddle-ridden vehicle for sports driving, alight-weight, small-size gearbox capable of rapid gear shift operationwithout such driving force interruption is desired.

SUMMARY

Embodiments of the present invention are made in consideration of such aproblem, and an object thereof is to provide a gearbox of asaddle-ridden vehicle that is capable of rapid gear shift operationwithout interruption of the driving force and is allowed to have lightweight and small size.

In one embodiment of the invention, there is provided a gearbox of asaddle-ridden vehicle. The gearbox has a transmission mechanism mountedon a saddle-ridden vehicle. Driving force generated by a power source isinput to the transmission mechanism. The transmission mechanism performsgear shift by a plurality of transmission gears on power train shaftsdivided for odd stages and even stages and outputs the driving force.The gearbox further has a clutch mechanism having a plurality ofclutches that allow mutually independent connection/disconnectionoperation and are each assigned to a respective one of the power trainshafts. The gearbox includes a gear change mechanism that is interlockedwith a change pedal shaft to which rotational force by operation of ashift pedal is transmitted and arbitrarily selects a transmission gearof the transmission mechanism to perform gear shift, and a controldevice that electronically controls connection/disconnection of theclutch mechanism according to the shift position of the gear changemechanism.

In another embodiment, the gear change mechanism can have a shift drumthat is rotated by foot operation of a driver and exclusively sets oneof the transmission gears to a dog-in state to link the driving force,and a gear position sensor that detects the rotation angle of the shiftdrum to detect the shift stage of the selected transmission gear. Thecontrol device receives a gear shift instruction by the driver based ona detection result of the gear position sensor and carries out controlto connect/disconnect the plurality of clutches.

In another embodiment, the gear change mechanism has an intermittentfeed mechanism that converts swing motion by the shift pedal torotational motion of the shift drum. A shift spindle rotation sensor islocated at the swing center of the intermittent feed mechanism and candetect the rotation angle of an interlocking shaft that interlocks theshift pedal with the shift drum. The control device receives a gearshift instruction by the driver based on a detection result of the gearposition sensor and carries out control to connect/disconnect theplurality of clutches.

In another embodiment, a stopper retaining part that has a circular discshape and has concave parts and convex parts alternately disposed atpredetermined angles is made in the shift drum. The gear changemechanism has a stopper portion that is biased against the stopperretaining part and stops rotation of the shift drum at a position atwhich the stopper portion gets into one of the concave parts to keep theshift drum at a predetermined shift stage. The control device startsconnection/disconnection control of the clutch mechanism if an angledetected by the gear position sensor surpasses an angle from the concavepart to the top of the next convex part and further surpasses apredetermined angle.

In another embodiment, the intermittent feed mechanism is configured bya ratchet mechanism. The predetermined angle is set to an angle that isequal to or larger than an angle at which the ratchet mechanism is resetand is equal to or smaller than an angle at which the shift pedalreaches a stopper position.

In another embodiment, the control device detects a predetermined anglesurpassing an angle to the next convex part in both forward rotation andreverse rotation of the shift drum to start connection/disconnectioncontrol of the clutch mechanism.

In another embodiment, an angle at which the control device startsconnection/disconnection of the clutch mechanism is set to the samepredetermined angle in both forward rotation and reverse rotation of theshift drum.

In another embodiment, the saddle-ridden vehicle includes a clutchoperation element allowing the clutch mechanism to carry outconnection/disconnection control in accordance with intention of thedriver. The control device receives an operation signal from the clutchoperation element to output a clutch connection/disconnectioninstruction to the clutch mechanism.

In another embodiment, the clutch operation element is configured by anelectronic system based on a switch measure operable by a single finger.

According to certain embodiments, the gear change mechanism configuringthe gearbox of a saddle-ridden vehicle is provided as a mechanism drivenby only manual operation (foot operation) based on shift pedal operationof the driver. Furthermore, the clutch mechanism is configured by theplural clutches assigned to the transmission gears of the odd stages andthe even stages and connection/disconnection of them is electronicallycontrolled according to the shift position of the gear change mechanism.Thus, while interruption of driving force in the clutch mechanism can beeliminated, gear shift of the gear change mechanism is made to depend onthe operation of the driver and thereby the driver is kept from feelingdelay in the time until gear shift completion. In addition, theelectronic drive system of the gear change mechanism can be reduced andsize reduction and weight reduction of the gearbox can be achieved.

In some embodiments, the gear shift instruction by the driver isdetected and the connection/disconnection control of the clutchmechanism is carried out based on the detection result of the gearposition sensor that detects the rotation angle of the shift drum of thegear change mechanism. Thus, the connection/disconnection timing of theclutch can be detected by utilizing the gear position sensor.Accordingly, without adding another sensor to detect the gear shiftinstruction by the driver, suppression of increase in the number ofsensors and simplification of the circuit configuration and algorithm ofthe control device can be achieved.

In certain embodiments, the shift spindle rotation sensor that detectsthe rotation angle of the interlocking shaft of the intermittent feedmechanism of the gear change mechanism is provided, and the gear shiftinstruction by the driver is detected to control the clutch mechanismbased on the detection result of this sensor. Due to this feature, gearshift intention of the driver can be surely detected and enhancement ofthe gear shift accuracy can be achieved.

In certain embodiments, connection/disconnection control of the clutchmechanism is started if the angle detected by the gear position sensorsurpasses the angle from the concave part of the stopper retaining partto the next convex part and surpasses the predetermined angle. Thus, itis recognized that gear shift operation is carried out and the clutchmechanism is controlled at the completion timing of the gear shiftoperation by the driver. Therefore, sure clutch control based on thegear shift operation can be carried out with high accuracy.

In certain embodiments, the predetermined angle at whichconnection/disconnection control of the clutch mechanism is started isset between the angle at which the ratchet mechanism is reset and theangle at which the shift pedal reaches the stopper position. Thereby,connection/disconnection control of the clutch mechanism is carried outin the state in which sure gear shift operation of the gearbox has beencarried out. Thus, sure clutch control can be carried out in associationwith gear shift operation.

In some embodiments, irrespective of whether the rotation of the shiftdrum is forward rotation or reverse rotation, the predetermined anglesurpassing the angle to the next convex part is detected andconnection/disconnection control of the clutch mechanism is started. Dueto this feature, sure clutch control based on gear shift operation canbe carried out with high accuracy in both shift-up and shift-down.

In some embodiments, the predetermined angle is set to the same angleirrespective of whether the rotation of the shift drum is forwardrotation or reverse rotation. Due to this feature, there is nodifference in the start timing of connection/disconnection of the clutchmechanism and the driver is not given an uncomfortable feeling ofconnection/disconnection of the clutch mechanism in shift-up orshift-down.

In certain embodiments, the clutch operation element enablingconnection/disconnection control of the clutch mechanism in accordancewith driver's intention is provided and the control device receives anoperation signal of this clutch operation element to output the clutchconnection/disconnection instruction so that theconnection/disconnection control of the clutch mechanism can be carriedout in accordance with driver's intention instead of automatic controlby the control device. Therefore, the clutch mechanism allowing clutchoperation from automatic clutch operation to manual clutch operation canbe configured through addition of the clutch operation element andsmall-scale change in the control device. Thus, the saddle-riddenvehicle permitting plural kinds of operation with the single vehicle canbe provided at low cost.

In certain embodiments, by employing an electronic switch measure as theclutch operation element, the operation load can be reduced comparedwith conventional mechanical switch measures. Thus, operation with asimple switch measure is allowed and reduction of the burden of drivingoperation can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing one example of a saddle-ridden vehicle onwhich a gearbox according to embodiments of the present invention ismounted.

FIG. 2 is a side view showing one example of an engine mounted on thesaddle-ridden vehicle.

FIG. 3 is a sectional view showing various kinds of members such as acrankshaft set in a crankcase of the engine.

FIG. 4 is a configuration diagram showing a gearbox according to a firstembodiment (first gearbox).

FIG. 5 is a block diagram showing a configuration of a hydraulic supplysystem.

FIG. 6 is an exploded perspective view showing a gearshift system and aclutch system attached to the crankcase.

FIG. 7 is an explanatory diagram showing a state of a ratchet mechanism,a shift arm, and a stopper arm in plan view when a shift drum center ispositioned to neutral.

FIG. 8 is an exploded perspective view showing the ratchet mechanism.

FIG. 9 is a perspective view showing the ratchet mechanism viewed fromthe backside.

FIG. 10 is an explanatory diagram showing the state of the ratchetmechanism, the shift arm, and the stopper arm in plan view when theshift drum center is rotated from neutral toward the first.

FIG. 11 is an explanatory diagram showing the state of the ratchetmechanism, the shift arm, and the stopper arm in plan view when theshift drum center is positioned to the first after the ratchet mechanismis reset.

FIG. 12 is an explanatory diagram showing the state of the ratchetmechanism, the shift arm, and the stopper arm in plan view when theshift drum center is rotated from the first toward the second.

FIG. 13 is an explanatory diagram showing the state of the ratchetmechanism, the shift arm, and the stopper arm in plan view when theshift drum center is positioned to the second after the ratchetmechanism is reset.

FIG. 14 is a circuit block diagram showing a control system of the firstgearbox.

FIG. 15 is a graph showing the relationship between a gear position anda drum rotation angle signal (voltage value).

FIG. 16 is an explanatory diagram showing changes in the shape of aprotrusion part of the shift drum center (petal shape), the in-gearstate of odd-stage gears, the in-gear state of even-stage gears, a gearposition determination value, and the drum rotation angle signal(voltage value), which are according to the rotation angle of the shiftdrum.

FIG. 17A is an explanatory diagram showing the breakdown of an odd-stagein-gear information table and FIG. 17B is an explanatory diagram showingthe breakdown of an even-stage in-gear information table.

FIG. 18 is a flowchart showing processing operation of the firstgearbox.

FIG. 19 is a flowchart showing determination processing in a target gearposition determiner of the first gearbox.

FIG. 20 is a flowchart showing determination processing in a connectionclutch determiner of the first gearbox.

FIG. 21 is a timing chart (of the case in which clutch shift isperformed) showing changes in the drum rotation angle signal (voltagevalue) associated with the operation position (operation amount) of ashift pedal, the gear position determination value, a target gearposition value, a connection clutch determination value, a first clutchcapacity output value, a second clutch capacity output value, thevehicle velocity, and the engine rotational speed.

FIG. 22 is a timing chart (of the case in which clutch shift is notperformed) showing changes in the drum rotation angle signal (voltagevalue) associated with the operation position (operation amount) of theshift pedal, the gear position determination value, the target gearposition value, the connection clutch determination value, the firstclutch capacity output value, the second clutch capacity output value,the vehicle velocity, and the engine rotational speed.

FIG. 23 is a development view of cam grooves of the shift drum.

FIG. 24 is a side view showing one example of a saddle-ridden vehicle onwhich a gearbox according to a second embodiment (second gearbox) ismounted.

FIG. 25 is a circuit block diagram showing a control system of thesecond gearbox.

FIG. 26 is a graph showing the relationship among the operation amountof a clutch lever, an output voltage value of an operation amountsensor, and manual operation clutch capacity.

FIG. 27 is a flowchart showing processing operation of the secondgearbox.

FIG. 28 is a flowchart showing determination processing in theconnection clutch determiner of the second gearbox.

FIG. 29 is a flowchart showing determination processing in a manualoperation clutch determiner of the second gearbox.

FIG. 30 is a flowchart showing processing in a clutch capacitycalculator of the second gearbox.

FIG. 31 is a flowchart showing the processing in the clutch capacitycalculator when a manual operation clutch determination value indicatesa first clutch.

FIG. 32 is a flowchart showing the processing in the clutch capacitycalculator when the manual operation clutch determination valueindicates a second clutch.

FIG. 33 is a timing chart (of the case in which clutch shift isperformed) showing changes in the drum rotation angle signal (voltagevalue) associated with the operation position (operation amount) of theshift pedal, the gear position determination value, the target gearposition value, the connection clutch determination value, the firstclutch capacity output value, and the second clutch capacity outputvalue.

DETAILED DESCRIPTION

Gearboxes of a saddle-ridden vehicle according to embodiment examples ofthe present invention will be described below with reference to FIGS. 1to 33.

First, a saddle-ridden vehicle 10 to which a gearbox according to thepresent embodiment is applied will be described with reference to FIGS.1 to 33.

As shown in FIG. 1, a vehicle body frame 12 of the saddle-ridden vehicle10 that is a saddle-ridden vehicle has a head pipe 18 that steerablysupports a front fork 16 rotatably supporting a front wheel 14, a pairof left and right main frames 20 extending from this head pipe 18rearward and downward, and a pair of left and right pivot plates 22 thatare provided continuously with rear parts of both the main frames 20 andextend downward. A rear wheel 26 is rotatably supported on a rear partof a swing arm 24 whose front end is swingably supported by a pivotplate 22. In addition, a link 28 is provided between a lower part of thepivot plate 22 and a front part of the swing arm 24, and a cushion unit30 is provided between an upper part of the pivot plate 22 and the link28.

A power unit 32 is suspended on a main frame 20 and the pivot plate 22and rotational power output from this power unit 32 is transmitted tothe rear wheel 26 via a drive shaft 34 extending forward and rearward.

A side stand 40 is attached to an engine main body 38 of an engine 36(power source) included in the power unit 32 or the vehicle body frame12. In this embodiment, the side stand 40 is attached to a lower part ofthe left pivot plate 22 in the vehicle body frame 12. Therefore, thesaddle-ridden vehicle 10 is inclined to the left when being parked withthe side stand 40 made upright.

A pair of left and right handles 42 are each attached to an upper endpart of the front fork 16. A grip part of the right handle 42 (notshown) is made as a throttle grip and a front brake lever is disposed infront of it. A clutch-OFF switch 44 (clutch operation element) todisconnect a clutch is disposed in front of a grip part of the lefthandle 42.

Left and right steps 46 for a driver are each attached to a rear part ofa respective one of the left and right pivot plats 22 with theintermediary of a step holder. In particular, in front of the left step46, a shift pedal 48 with which gear shift operation (shift operation)by manual operation (foot operation) is carried out is disposed.

As shown in FIG. 2, the engine main body 38 of the engine 36 isconfigured as a V-shape water-cooled engine. It has a front bank 50Flocated forward in the state in which the engine main body 38 is mountedon the saddle-ridden vehicle 10 and a rear bank 50R located morerearward than this front bank 50F. A crankshaft 54 along a left-rightdirection of the saddle-ridden vehicle 10 is rotatably supported by acrankcase 52 common to both the banks 50F and 50R.

The crankcase 52 is configured by coupling of an upper case half body 52a and a lower case half body 52 b. Front and rear cylinder blocks 56Fand 56R are formed monolithically with the upper case half body 52 a insuch a manner as to form a V-character. An axis line of the crankshaft54 is disposed on a coupling plane 58 of the upper case half body 52 aand the lower case half body 52 b.

The front bank 50F is configured by the front cylinder block 56F, afront cylinder head 60F coupled to the front cylinder block 56F, and afront head cover 62F coupled to the front cylinder head 60F. The rearbank 50R is configured by the rear cylinder block 56R, a rear cylinderhead 60R coupled to the rear cylinder block 56R, and a rear head cover62R coupled to the rear cylinder head 60R. An oil pan 64 is coupled to alower part of the crankcase 52.

Two cylinder bores 66 arranged along the axis line of the crankshaft 54are formed in the front cylinder block 56F, and the front cylinder block56F is so coupled to the crankcase 52 that axis lines of the cylinderbores 66 are inclined forward in the state in which the engine main body38 is suspended on the vehicle body frame 12. Furthermore, two cylinderbores 66 arranged along the axis line of the crankshaft 54 are formed inthe rear cylinder block 56R, and the rear cylinder block 56R is socoupled to the crankcase 52 that axis lines of the respective cylinderbores 66 are inclined rearward in the state in which the engine mainbody 38 is suspended on the vehicle body frame 12. Moreover, pistons 68slidably fitted in both the cylinder bores 66 of the front bank 50F andpistons 68 slidably fitted in both the cylinder bores 66 of the rearbank 50R are connected to the crankshaft 54 in common.

As shown in FIG. 3, in the front cylinder head 60F, a pair of intakevalves 70 are disposed for each of the cylinder bores 66 in such amanner as to be biased toward a valve-closing direction by a pair ofvalve springs 72 and be capable of open/close actuation. In addition, apair of exhaust valves (not shown) are disposed for each of the cylinderbores 66 in such a manner as to be biased toward the valve-closingdirection by valve springs and be capable of open/close actuation. Theseintake valves 70 and exhaust valves are open/close-driven by afront-bank valve actuator 74F.

The front-bank valve actuator 74F includes a camshaft 76 that isrotatably supported by the front cylinder head 60F with an axis lineparallel to the crankshaft 54 and is disposed above the intake valves70. Intake valve lifters 80 are set between plural (four, in thisembodiment) intake cams 78 provided on this camshaft 76 and the intakevalves 70 and are slidably fitted in the front cylinder head 60F. Arocker arm is provided, and has, at one end, a roller in rolling contactwith plural (four, in this embodiment) exhaust cams (not shown) providedon the camshaft 76. In addition, to the other end of the rocker arm, atappet screw abutting against upper ends of stems of the respectiveexhaust valves is so screwed that its advance/retreat position can beadjusted. The rocker arm is swingably supported by a rocker shaft thathas an axis line parallel to the camshaft 76 and is fixedly disposed onthe front cylinder head 60F.

In the rear cylinder head 60R, a pair of intake valves 70 and a pair ofexhaust valves are so disposed for each of the cylinder bores 66 as tobe biased toward the valve-closing direction by valve springs and becapable of open/close actuation. These intake valves 70 and exhaustvalves are open/close-driven by a rear-bank valve actuator (not shown).

An electric generator 82 is coupled to a left end part of the crankshaft54 in the state in which the engine main body 38 is mounted on thevehicle body frame 12. This electric generator 82 is composed of a rotor84 fixed to the crankshaft 54 and a stator 86 fixedly disposed in therotor 84 and is housed in a generator housing chamber 90 composed of thecrankcase 52 and a generator cover 88 coupled to a left side surface ofthis crankcase 52. The stator 86 is fixed to the generator cover 88.

In addition, a gear 94 is coupled to the rotor via a one-directionclutch 92 enabling power transmission toward the rotor 84 and power froma starter motor (not shown) is transmitted to this gear 94.

To a right side surface of the crankcase 52 in the state in which theengine main body 38 is mounted on the vehicle body frame 12, a clutchcover 98 that forms a clutch chamber 96 with the crankcase 52 iscoupled. In the clutch chamber 96, drive sprockets 100 and 102 arefixedly provided on the crankshaft 54. One drive sprocket 100 serves aspart of a front-bank timing transmission mechanism 104 that transmitsrotational power of the crankshaft 54 to the camshaft 76 in thefront-bank valve actuator 74F at a reduction ratio of 1/2. In thefront-bank timing transmission mechanism 104, an endless cam chain 108is wound on the drive sprocket 100 and a driven sprocket 106 provided onthe camshaft 76. The other drive sprocket 102 serves as part of arear-bank timing transmission mechanism 110 that transmits therotational power of the crankshaft 54 to intake and exhaust camshafts inthe rear-bank valve actuator (not shown) at a reduction ratio of 1/2. Inthis rear-bank timing transmission mechanism 110, an endless cam chain112 is wound on the drive sprocket 102 and driven sprockets (not shown)provided on the intake and exhaust camshafts, respectively.

A cam chain chamber 114 in which the cam chain 108 is made to travel isformed in the front cylinder block 56F and the front cylinder head 60F.A cam chain chamber (not shown) in which the cam chain 112 is made totravel is formed in the rear cylinder block 56R and the rear cylinderhead 60R.

As shown in FIG. 4, a gearbox according to a first embodiment(hereinafter, referred to as first gearbox 200A) is set on a powertransmission path between the crankshaft 54 and the drive shaft 34. Thefirst gearbox 200A includes a primary reduction mechanism 202 (see FIG.3), a clutch system 204 (clutch mechanism), a gear transmissionmechanism 206 (transmission mechanism), and a drive train shaft 210 inthat order from the side of the crankshaft 54. The primary reductionmechanism 202 and the clutch system 204 are housed in the clutch chamber96 and the gear transmission mechanism 206 is housed in the crankcase52.

As shown in FIG. 4, the gear transmission mechanism 206 has a main shaft212 and a countershaft 214 (output shaft) each disposed in parallel tothe crankshaft 54 (see FIG. 3). The drive train shaft 210 is alsodisposed in parallel to the crankshaft 54. The crankshaft 54, the mainshaft 212, and the countershaft 214 are disposed at positionscorresponding to the coupling plane 58 of the upper case half body 52 a(see FIG. 2) and the lower case half body 52 b, and the drive trainshaft 210 is disposed in front of and below the countershaft 214. Acrank-side drive gear 216 of the primary reduction mechanism 202 isfixed to an end of the crankshaft 54 on the side of the cam chainchamber 114 (see FIG. 3) and meshes with a main-side driven gear 218 ofthe main shaft 212. The main-side driven gear 218 is provided on themain shaft 212 rotatably relative to the main shaft 212 as describedlater and is connected to the clutch system 204. Due to actuation ofthis clutch system 204, power transmission between the crankshaft 54 andthe main shaft 212 can be broken. A drive sprocket 220 is engaged withthe main-side driven gear 218 and rotates integrally with the main-sidedriven gear 218 irrespective of whether the clutch system 204 is in theon-state or off-state. As shown in FIG. 2, the drive sprocket 220transmits rotation of the main shaft 212 to a driven sprocket 224 fixedto a pump shaft of an oil pump 222 via a drive chain 226 to drive theoil pump 222.

As shown in FIG. 4, drive gears m1 to m6 (a plural-gear group providedon first and second input shafts) for six speeds are provided on themain shaft 212, and driven gears n1 to n6 (gear group meshing with thegear group, gears of the output shaft) for six speeds are provided onthe countershaft 214. The respective drive gears m1 to m6 and drivengears n1 to n6 mesh with each other between the corresponding shiftstages and configure transmission gear pairs corresponding to therespective shift stages.

A mission case 228 is monolithically continuous with a rear part of thecrankcase 52 (see FIG. 3) and the first gearbox 200A includes, in themission case 228, the clutch system 204 that connects and disconnectsinput from the crankshaft 54 (see FIG. 3) and a gearshift system 208(gear change mechanism) that performs gear shift. The saddle-riddenvehicle 10 has an ECU (Engine Control Unit) 230 acting as a controldevice to control the clutch system 204 and the gearshift system 208,and the first gearbox 200A including the clutch system 204, thegearshift system 208, and the ECU 230 as its main constituent elementsis configured. In FIG. 4, wiring to the ECU 230 is omitted in order toavoid complicated diagrammatic representation.

The first gearbox 200A has the above-described main shaft 212 with aninner-outer dual structure having an inner shaft 212 m (one power trainshaft) and an outer shaft 212 n (an other power train shaft). Thecountershaft 214 and the drive train shaft 210 are disposed in parallelto this main shaft 212. The above-described transmission gear groups m1to m6 and n1 to n6 are disposed astride the main shaft 212 and thecountershaft 214. The clutch system 204 is coaxially disposed at a rightend part of the main shaft 212. A hydraulic supply system (see FIG. 5)supplies hydraulic pressure for actuation to this clutch system 204. Theassembly including the main shaft 212, the countershaft 214, thetransmission gear groups m1 to m6 and n1 to n6, and the drive trainshaft 210 is treated as a transmission 232.

In the main shaft 212, a right part of the inner shaft 212 m laterallyextending is relatively rotatably inserted in the outer shaft 212 n asshown in FIG. 4. This inner shaft 212 m is rotatably supported by theouter shaft 212 n with the intermediary of a bearing. The drive gears m1to m6 for six speeds in the transmission gear groups are disposed onouter circumferences of the inner shaft 212 m and the outer shaft 212 nin a distributed manner. The driven gears n1 to n6 for six speeds in thetransmission gear groups are disposed on an outer circumference of thecountershaft 214. The respective drive gears m1 to m6 and driven gearsn1 to n6 mesh with each other between the corresponding shift stages andconfigure the transmission gear pairs corresponding to the respectiveshift stages. The respective transmission gear pairs have a smallerreduction ratio (serve as higher-speed gear) in the order from the firstto the sixth.

A left end part of the inner shaft 212 m reaches a left wall of themission case 228 and is rotatably supported on this left wall with theintermediary of a ball bearing 234. A right part of the inner shaft 212m penetrates a right wall of the mission case 228 to face the inside ofthe clutch chamber 96, and a laterally intermediate part of this innershaft 212 m is rotatably supported on the right wall of the mission case228 with the intermediary of a laterally intermediate part of the outershaft 212 n penetrating the right wall likewise and a ball bearing 236.The clutch chamber 96 is configured by the clutch cover 98 covering theclutch system 204 from the outside.

The outer shaft 212 n is shorter than the inner shaft 212 m and its leftend part terminates at a laterally intermediate part of the mission case228. The drive gears m2, m4, and m6 corresponding to even shift stages(second, fourth, sixth) are supported at sites on the outer shaft 212 nlocated more leftward than the right wall of the mission case 228. Thedrive gears m1, m3, and m5 corresponding to odd shift stages (first,third, fifth) are supported at sites on the inner shaft 212 m locatedmore leftward than the left end of the outer shaft 212 n (an end part ofan outside input shaft).

Left and right end parts of the countershaft 214 are rotatably supportedon the left and right walls of the mission case 228 with theintermediary of bearings 238 and 240. A gear 242 is coupled to the rightend part of the countershaft 214 and always meshes with a gear 244 ofthe drive train shaft 210. The drive train shaft 210 is rotatablysupported on the left and right walls of the mission case 228 with theintermediary of bearings 246 and 248. A torque damper 250 is disposedfor the drive train shaft 210. The torque damper 250 is a component thatalleviates torque variation when it is applied, and has a cylindricalmember 252 axially movably spline-coupled to the drive train shaft 210.A spring retaining member 254 is fixed to the drive train shaft 210. Acoil spring 256 is provided between the cylindrical member 252 and thespring retaining member 254 and the cylindrical member 252 is biasedtoward the gear 244.

A drive bevel gear 258 is monolithically provided at a left end part ofthe drive train shaft 210 and meshes with a driven bevel gear 262provided monolithically with a front end of a shaft portion 260. Theshaft portion 260 is coupled to the drive shaft 34 (FIG. 1) extendingalong a front-rear direction of the vehicle body. This transmitsrotation of the drive train shaft 210 to the drive shaft 34.

At sites on the countershaft 214 located inside the mission case 228,the driven gears n1 to n6 corresponding to the respective shift stagesin the transmission gear groups are supported in the same order as thatof the respective drive gears m1 to m6. An in-shaft oil path to supplyoil from the oil pump 222 is formed inside each of the inner shaft 212 mand the countershaft 214 and the oil is accordingly supplied to therespective transmission gear groups via these in-shaft oil paths.

The clutch system 204 is coaxially disposed at the right end part of themain shaft 212. The clutch system 204 is set between the crankshaft 54(see FIG. 3) of the engine 36 and the main shaft 212 and adjusts theconnection state of the crankshaft 54 and the main shaft 212.

This clutch system 204 has hydraulic odd-stage disc clutch andeven-stage disc clutch (hereinafter, referred to simply as first clutch264 a and second clutch 264 b) disposed coaxially with and adjacent toeach other (clutch mechanism). These first clutch 264 a and secondclutch 264 b are coaxially provided at right ends of the inner shaft 212m and the outer shaft 212 n. The first clutch 264 a is provided for theinner shaft 212 m and the second clutch 264 b is provided for the outershaft 212 n.

The main-side driven gear 218 meshing with the crank-side drive gear 216of the crankshaft 54 is coaxially provided for a clutch outer 266 sharedby the first clutch 264 a and the second clutch 264 b, and rotationaldriving force from the crankshaft 54 is input to the clutch outer 266via these crank-side drive gear 216 and main-side driven gear 218. Therotational power input to the clutch outer 266 is individuallytransmitted to the inner shaft 212 m and the outer shaft 212 n accordingto the connection states of the first clutch 264 a and the second clutch264 b.

The connection states of the first clutch 264 a and the second clutch264 b are individually controlled depending on whether hydraulic supplyfrom a hydraulic supply system 268 shown in FIGS. 2 and 5 is present orabsent.

As shown in FIGS. 2 and 5, the hydraulic supply system 268 has a clutchcontrol device 270 and the above-described oil pump 222 that pumps upoil 272 (see FIG. 5) in the oil pan 64 and supplies it to the clutchsystem 204. The clutch control device 270 has a firstelectromagnetically-controlled valve 274 a and a secondelectromagnetically-controlled valve 274 b.

As shown in FIG. 2, the first electromagnetically-controlled valve 274 aand the second electromagnetically-controlled valve 274 b are disposedat positions different in the front-rear direction and anupward-downward direction. In addition, the secondelectromagnetically-controlled valve 274 b is disposed more upward thanthe first electromagnetically-controlled valve 274 a and more upwardthan the crankshaft 54, and at least part of, in this embodiment mostpart of, the first electromagnetically-controlled valve 274 a disposedbelow is disposed more forward than the crankshaft 54.

As shown in FIG. 5, the first electromagnetically-controlled valve 274 adraws and supplies the oil 272 from the oil pump 222 from and to thefirst clutch 264 a based on an instruction (first clutch capacity outputvalue Sc1) from the ECU 230. By the supply of the oil 272 to the firstclutch 264 a, the inner shaft 212 m of the main shaft 212 is connectedto the crankshaft 54. By the removal of the oil 272 from the firstclutch 264 a, this connection is broken. The oil 272 removed from thefirst clutch 264 a is returned to the oil pan 64.

The second electromagnetically-controlled valve 274 b draws and suppliesthe oil 272 from the oil pump 222 from and to the second clutch 264 bbased on an instruction (second clutch capacity output value Sc2) fromthe ECU 230. By the supply of the oil 272 to the second clutch 264 b,the outer shaft 212 n of the main shaft 212 is connected to thecrankshaft 54. By the removal of the oil 272 from the second clutch 264b, this connection is broken. The oil 272 removed from the second clutch264 b is returned to the oil pan 64.

Normally, one of the first clutch 264 a and the second clutch 264 b isset to the connected state and the other is set to the disconnectedstate. Furthermore, power transfer in the transmission 232 is carriedout by using any transmission gear pair coupled to one of the innershaft 212 m and the outer shaft 212 n, and the transmission gear pair tobe used next is selected in advance among the transmission gear pairscoupled to the other of the inner shaft 212 m and the outer shaft 212 n.From this state, one clutch in the connected state, of the first clutch264 a and the second clutch 264 b, is set to the disconnected state andthe other clutch in the disconnected state thus far is set to theconnected state. This switches the power transfer of the transmission232 to power transfer carried out by using the transmission gear pairselected in advance. Thereby, shift-up or shift-down of the transmission232 is made.

Specifically, the first clutch 264 a is connected at the first, third,and fifth and the second clutch 264 b is connected at the second,fourth, and sixth. That is, in the clutch system 204, the first clutch264 a and the second clutch 264 b are alternately connected anddisconnected on each one shift stage basis from the first to the sixthto perform gear shift. In particular, in the process of shift-up orshift-down, both the first clutch 264 a and the second clutch 264 b areconnected as described later.

As shown in FIG. 4, the transmission 232 is a constant mesh type inwhich the drive gears m1 to m6 and the driven gears n1 to n6corresponding to the respective shift stages always mesh with eachother. The respective gears m1 to m6 and n1 to n6 are roughly classifiedinto the following three gears: fixed gear that is rotatable integrallywith its support shaft (main shaft 212, countershaft 214); free gearthat is rotatable relative to the support shaft and is axiallyimmovable; and slide gear that is rotatable integrally with the supportshaft and is axially movable. Specifically, the drive gears m1 and m2are set as fixed gears, the drive gears m3 and m4 are set as slidegears, and the drive gears m5 and m6 are set as free gears. The drivengears n1 to n4 are set as free gears and the driven gears n5 and n6 areset as slide gears. Hereinafter, the drive gears m3 and m4 and thedriven gears n5 and n6 will be referred to as the slide gear, and thedrive gears m5 and m6 and the driven gears n1 to n4 will be referred toas the free gear. Each slide gear is spline-fitted to its support shaft.

An axially-protruding dog is made on a side surface of the slide gear m3(gear provided on an inside input shaft) and this dog can be coupled toa dog hole of the free gear m5. For the slide gear n5, a dog is made oneach of both sides in the axial direction. One of the dogs can becoupled to a dog hole of the free gear n1 and the other can be coupledto a dog hole of the free gear n3.

A dog is made for the slide gear m4 (gear provided at the end part ofthe outside input shaft) and this dog can be coupled to a dog hole ofthe free gear m6. Furthermore, a dog axially protruding toward theopposite side to the dog is made for the slide gear m4 and this dog canbe coupled to a dog hole made in the slide gear m3.

For the slide gear n6, a dog is made on each of both sides. One of thedogs can be coupled to a dog hole of the free gear n2 and the other canbe coupled to a dog hole of the free gear n4.

The respective dogs and the respective dog holes are so engaged witheach other that the corresponding slide gear and free gear are incapableof rotating relative to each other when these gears get close to eachother, and this engagement is broken when the slide gear and the freegear get separated from each other. Furthermore, any of the respectiveslide gears and the corresponding free gear are so engaged with eachother via the dog as to be incapable of relative rotation, and therebythe free gear is fixed to the support shaft. This enables powertransmission with selective use of the transmission gear pair of any ofthe first to the sixth between the main shaft 212 and the countershaft214. In the state in which all engagements between the respective slidegears and free gears are broken, the power transmission between the mainshaft 212 and the countershaft 214 is impossible and the neutral stateis obtained.

The drive gear m4 provided at the left end of the outer shaft 212 n andthe drive gear m3 of the inner shaft 212 m adjacent to the drive gear m4are so slid that the drive gear m4 and the drive gear m3 come close toeach other, and are integrally connected by coupling of the dog of thedrive gear m4 to the dog hole of the drive gear m3. In this state, theouter shaft 212 n and the inner shaft 212 m are integrally connected viathe drive gears m3 and m4 and the outer shaft 212 n and the inner shaft212 m can integrally rotate in synchronization. When the drive gear m4and the drive gear m3 are so slid as to get separated from each other,the coupling of the dog of the drive gear m4 to the dog hole of thedrive gear m3 is broken, so that the connection between the outer shaft212 n and the inner shaft 212 m is broken.

That is, the dog of the drive gear m4 and the dog hole of the drive gearm3 configure a dog clutch (synchronizing measure) capable of switchingthe connection state of the outer shaft 212 n and the inner shaft 212 m.This dog clutch is a measure to synchronize the rotation of the outershaft 212 n and that of the inner shaft 212 m.

Next, the gearshift system 208 will be described. As shown in FIG. 4,the gearshift system 208 moves four shift forks (first shift fork 280 a,second shift fork 280 b, third shift fork 280 c, and fourth shift fork280 d) in the axial direction by rotation of a cylindrical shift drum278 disposed in parallel to the main shaft 212 and the countershaft 214,and switches the transmission gear pair (shift stage) used for powertransmission between the main shaft 212 and the countershaft 214. In anouter circumferential surface of the shift drum 278, four cam grooves(first cam groove 282 a, second cam groove 282 b, third cam groove 282c, and fourth cam groove 282 d) to which the first shift fork 280 a tothe fourth shift fork 280 d are fitted are formed. The first cam groove282 a to the fourth cam groove 282 d are formed along a circumferentialdirection of the shift drum 278.

The second shift fork 280 b extends toward the main shaft 212 and isfitted into a recess P3 of the slide gear m3 and the third shift fork280 c is fitted into a recess P4 of the slide gear m4. The first shiftfork 280 a and the fourth shift fork 280 d extend toward thecountershaft 214. The first shift fork 280 a is fitted into a recess P5of the slide gear n5 and the fourth shift fork 280 d is fitted into arecess P6 of the slide gear n6. Base end sides of the first shift fork280 a to the fourth shift fork 280 d are each axially movably supportedby a pair of shift fork rods (first shift fork rod 284 a and secondshift fork rod 284 b). Sliding protrusions 286 engaged with the firstcam groove 282 a to the fourth cam groove 282 d of the shift drum 278are provided on the base end sides of the first shift fork 280 a to thefourth shift fork 280 d.

A right end of the shift drum 278 in FIG. 4 is coupled to a shiftspindle 290 (interlocking shaft) via a ratchet mechanism 288(intermittent feed mechanism) that controls the rotation amount of theshift drum 278.

A base end part of a shift lever 292 is fitted and fixed to a tip part290 a of the shift spindle 290 protruding from the mission case 228 asshown in FIG. 1. This shift lever 292 is linked to the shift pedal 48via a shift rod 294.

Specifically, a boss part 292 a as the base end part of the shift lever292 is serration-fitted to the tip part 290 a of the shift spindle 290.A slit is made in the boss part 292 a and the shift lever 292 and theshift spindle 290 are fixed by tightening this slit by using a bolt. Atip side of the shift lever 292 extends rearward and an upper end partof the shift rod 294 is pivotally coupled to a tip part 292 b (changepedal shaft) of the shift lever 292.

The shift pedal 48 is so provided that its base end part 48 a ispivotally supported by a lower end part of the pivot plate 22 and thetip side obliquely extends toward the rear upper side. A tip part 48 bof the shift pedal 48 is disposed at such a position that it can beoperated by driver's left foot carried on the left step 46. A lower endpart of the shift rod 294 is pivotally coupled to between the base endpart 48 a and the tip part 48 b of this shift pedal 48, so that a shiftlink mechanism by the shift pedal 48, the shift rod 294, and the shiftlever 292 is formed. By operation of the shift pedal 48, the shiftspindle 290 and a shift arm 296 rotate by a certain angle via the shiftrod 294 and the shift lever 292 as shown in FIG. 4.

As shown in FIGS. 4, 6, and 7, a shift drum center 298 that turnstogether with the shift drum 278 is fixed to one end of the shift drum278 by a coaxial bolt 300 and a shift drum pin 302 attached at aneccentric position. As shown in FIG. 6, this shift drum center 298 has apetal-like protrusion part 304 (stopper retaining part) with pluralnotches formed along its outer circumference at a part opposed to theshift drum 278. Furthermore, the shift drum center 298 has a housingpart 306 in which part of the ratchet mechanism 288 to be describedlater is housed at a part on the opposite side to the shift drum 278.

As shown in FIG. 7, a neutral notch N_(N) for locating each of theabove-described recesses P3 to P6 to the neutral position is formed inan outer circumference of the protrusion part 304. A first notch N₁ isformed adjacent to this neutral notch N_(N) in the anticlockwisedirection across a first convex part K₁ for example. A second notch N₂is formed adjacent to the first notch N₁ across a second convex part K₂.A third notch N₃ is formed adjacent to the second notch N₂ across athird convex part K₃. A fourth notch N₄ is formed adjacent to the thirdnotch N₃ across a fourth convex part K₄. A fifth notch N₅ is formedadjacent to the fourth notch N₄ across a fifth convex part K₅. A sixthnotch N₆ is formed adjacent to the fifth notch N₅ across a sixth convexpart K₆. The pitches of the first notch N₁ to the sixth notch N₆ (centerangle θ_(a)) are each substantially 60 degrees (59 degrees to 61degrees). The respective pitches between the neutral notch N_(N) and thefirst notch N₁ and between the neutral notch N_(N) and the sixth notchN₆ (center angle θ_(b)) are each substantially 30 degrees (29 degrees to31 degrees).

A stopper arm 308 (stopper portion) is selectively engaged with theneutral notch N_(N) and the first notch N₁ to the sixth notch N₆ made inthe protrusion part 304 of the shift drum center 298. As shown in FIG.6, this stopper arm 308 is composed of an arm 312 and a roller 314. Abase end part of the arm 312 is pivotally supported on the upper casehalf body 52 a (see FIG. 6) in the crankcase 52 by a support shaft 310having an axis line parallel to an axis line of the shift drum 278 andthe shift drum center 298. The roller 314 is rotatably supported by atip of the arm 312 in such a manner as to be engaged with one of theneutral notch N_(N) and the first notch N₁ to the sixth notch N₆.

Of these notches, the neutral notch N_(N) is formed into an arc-likeconcave shape in order to stabilize the engagement state of the roller314. The other notches, the first notch N₁ to the sixth notch N₆, areformed by a curve almost close to a straight line except for that thebottom of the notch is slightly bent. That is, in the case of the firstnotch N₁ for example, a curved surface almost close to an inclinedsurface is made from the bottom of the first notch N₁ to the top of thesecond convex part K₂.

As shown in FIGS. 6 and 7, a torsion spring 316 is set between the baseend part of the arm 312 and the upper case half body 52 a. The arm 312,i.e. the stopper arm 308, is biased toward the rotation center of theshift drum center 298 by spring force exerted by the torsion spring 316in order to engage the roller 314 with one of the neutral notch N_(N)and the first notch N₁ to the sixth notch N₆.

In shift from neutral to the first and shift from the first to neutral,the shift drum center 298 is rotationally driven by subsequently 30degrees by the ratchet mechanism 288. In shift from the first to thesecond, from the second to the third, or the like, it is rotationallydriven by subsequently 60 degrees by the ratchet mechanism 288.

The ratchet mechanism 288 has a drum shifter 318, a pair of ratchetpawls 320, and a pair of springs 322. The drum shifter 318 can rotateabout an axis line coaxial with the shift drum center 298 and at leastpart thereof is disposed in the shift drum center 298. As shown in FIGS.8 and 9, the ratchet pawls 320 are symmetrically mounted on the drumshifter 318 in such a manner as to stand and fall in a radial directionof the drum shifter 318. The springs 322 bias these ratchet pawls 320 ina standing direction. The ratchet mechanism 288 further has engagementrecesses 324 and a fixed guide plate 326. The engagement recesses 324are made in an inner circumference of the shift drum center 298 at equalintervals in the circumferential direction and the ratchet pawls 320 canbe engaged with the engagement recesses 324. The guide plate 326 guidesthe stood/laid state of the ratchet pawls 320 depending on the rotationof the drum shifter 318.

The drum shifter 318 is so supposed as to be capable of rotating aboutan axis line of the bolt 300 (see FIG. 6), which connects the shift drumcenter 298 to one end of the shift drum 278 coaxially.

As shown in FIG. 8, the ratchet pawls 320 are biased in the standingdirection by the springs 322. Tip parts thereof protrude from an outercircumference of the drum shifter 318 in the stood state and the tipparts exist at substantially the same positions as that of the outercircumference of the drum shifter 318 in the laid state.

In the inner circumference of the shift drum center 298, the plural(six, in this embodiment) engagement recesses 324 are made at equalintervals in the circumferential direction. In the state in which thestopper arm 308 is engaged with one of the first notch N₁ to the sixthnotch N₆, the tip parts of the ratchet pawls 320 can be selectivelyengaged with two engagement recesses 324 opposed to each other among therespective engagement recesses 324.

As shown in FIG. 6, the guide plate 326 is fastened to the upper casehalf body 52 a by a pair of bolts at such a position that the shift drumcenter 298 exists between the guide plate 326 and the upper case halfbody 52 a. As shown in FIG. 8, a guide hole 328 corresponding to thedrum shifter 318 is made in this guide plate 326.

This guide hole 328 is composed of a larger-diameter arc part 328 a thathas the center at a rotational axis line of the shift drum center 298and the drum shifter 318, i.e. an axis line 330 of the bolt, and isformed with a diameter larger than the outer circumference of the drumshifter 318. A restricting protrusion 328 b protrudes from a center partof this larger-diameter arc part 328 a more inward than the outercircumference of the drum shifter 318. A smaller-diameter arc part 328 cthat has the center at the axis line 330 of the bolt is formed with adiameter smaller than the outer circumference of the drum shifter 318.Step parts 328 d link both ends of the larger-diameter arc part 328 aand both ends of the smaller-diameter arc part 328 c. As shown in FIG.7, the circumferential length of the larger-diameter arc part 328 a isset to the length corresponding to that between two engagement recesses324 with which the tip parts of the two ratchet pawls 320 are engaged.

In addition, when a ratchet pawl 320 engaged with an engagement recess324 moves toward the smaller-diameter arc part 328 c in association withthe rotation of the drum shifter 318, a step part 328 d abuts againstthis ratchet pawl 320 to press this ratchet pawl 320 into the laidstate. The step parts 328 d are disposed more outward than the innercircumference of the shift drum center 298.

As shown in FIGS. 6 and 7, to the shift spindle 290, the shift arm 296that has a base end part fixed to the shift spindle 290 and extendstoward the drum shifter 318 along a radial direction of the shiftspindle 290 is fixed. This shift arm 296 extends long along the radialdirection of the shift spindle 290 and an engagement pin 336 implantedto the drum shifter 318 at a position offset from a rotational axis lineof the drum shifter 318 is engaged with an engagement hole 334 as anelongate hole made at a tip part of the shift arm 296.

Furthermore, as shown in FIG. 7, an arm 338 that forms a substantiallyL-shape with the shift arm 296 and extends along the radial direction ofthe shift spindle 290 is monolithically provided continuously with thebase end part of the shift arm 296, and an elongate hole 340 is made ata tip part of this arm 338.

As shown in FIGS. 6 and 7, a pin 342 inserted in the elongate hole 340is implanted to the upper case half body 52 a in the crankcase 52 and aclamp spring 344 having at its both ends a pair of clamp arms 344 a thatsandwich the pin 342 from both sides is so disposed between the shiftarm 296 and the arm 338 and the upper case half body 52 a as to surroundthe shift spindle 290. This makes the shift arm 296 and the arm 338 bebiased to such a neutral position that the pin 342 exists on a straightline coupling a circumferential center of the elongate hole 340 and anaxis line of the shift spindle 290.

Therefore, for example in shift from neutral to the first, from thestate of FIG. 7, the shift drum center 298 rotates by rotational drivingof the ratchet mechanism 288 in association with rotation of the shiftspindle 290, and the roller 314 of the stopper arm 308 gets into thefirst notch N₁ as shown in FIG. 10. Thereafter, as shown in FIG. 11, thedrum shifter 318 rotationally reverts to the original position due tobiasing of the clamp spring 344 and thereby reset operation of theratchet mechanism 288 is carried out. Thereafter, the roller 314 of thestopper arm 308 is located at the bottom of the first notch N₁ (stageresulting from rotation by substantially 30 degrees from the neutralposition) and thereby the rotation of the shift drum center 298 stops.

This applies also to shift from the first to the second for example.Specifically, from the state of FIG. 11, the shift drum center 298rotates by rotational driving of the ratchet mechanism 288 inassociation with rotation of the shift spindle 290, and the roller 314of the stopper arm 308 gets into the second notch N₂ as shown in FIG.12. Thereafter, as shown in FIG. 13, the drum shifter 318 rotationallyreverts to the original position due to biasing of the clamp spring 344,and thereby reset operation of the ratchet mechanism 288 is carried out.Thereafter, the roller 314 of the stopper arm 308 is located at thebottom of the second notch N₂ (stage resulting from rotation bysubstantially 60 degrees from the bottom of the first notch N₁) andthereby the rotation of the shift drum center 298 stops. This appliesalso to shift from the second to the fourth, shift from the fourth tothe fifth, and so forth. Furthermore, this applies also to shift-downoperation from the second to the first and so forth.

As shown in FIG. 14, the ECU 230 of the first gearbox 200A has a gearposition determiner 346, a target gear position determiner 348, adriving state determiner 350, a connection clutch determiner 354, and afirst clutch capacity calculator 356A.

The gear position determiner 346 determines the present gear positionand outputs it as a gear position determination value Da based on a drumrotation angle signal Sa from a drum rotation angle sensor 358 (gearposition sensor) that detects the rotation angle of the shift drum 278,an odd-stage in-gear information table 360, and an even-stage in-gearinformation table 362. The gear position determination value Da includes“N−N,” “1−N,” “1−2,” “N−2,” “3−2,” “3−N,” “3−4,” and so forth. Theelement in front of “−” denotes the state of the odd stage and theelement behind “−” denotes the state of the even stage.

The relationship between the present gear position and the drum rotationangle signal Sa (voltage value Va) is as shown in FIGS. 15 and 16 forexample.

Specifically, the drum rotation angle signal Sa (voltage value Va)proportionally rises in association with shift-up of the gear positiondetermination value Da. FIG. 16 is an explanatory diagram showingchanges in the shape of the protrusion part 304 of the shift drum center298 (petal shape), the in-gear state of the odd-stage gears, the in-gearstate of the even-stage gears, the gear position determination value Da,and the drum rotation angle signal Sa (voltage value Va), which areaccording to the rotation angle of the shift drum 278.

In FIG. 16, La represents a movement amount (angle) of the shift drum278 from the bottom of the notch to the top of the convex part adjacentin a gear shift direction. Lb represents the movement amount (angle) ofthe shift drum 278 from the bottom of the notch via the convex partadjacent in the gear shift direction to a point at which gear shift tothe next stage is permitted (shift permission threshold). Lc representsthe movement amount (angle) of the shift drum 278 from the bottom of thenotch via the convex part adjacent in the gear shift direction to thearrival of the shift pedal 48 at a stopper position of the shift-up sidedue to abutting of the pin 342 against an edge of the elongate hole 340of the arm 338. As signs “+” and “−” added to La, Lb, and Lc, “+”represents shift-up and “−” represents shift-down.

As shown in FIG. 17A, in the odd-stage in-gear information table 360, afirst voltage range V_(1f) to V_(1e) of the drum rotation angle signalSa (voltage value Va) in which the first gear is in the in-gear state, athird voltage range V_(3f) to V_(1e) in which the third gear is in thein-gear state, and a fifth voltage range V_(5f) to V_(5e) in which thefifth gear is in the in-gear state are registered.

Similarly, as shown in FIG. 17B, in the even-stage in-gear informationtable 362, a second voltage range V_(2f) to V_(2e) in which the secondgear is in the in-gear state, a fourth voltage range V_(4f) to V_(4e) inwhich the fourth gear is in the in-gear state, and a sixth voltage rangeV_(6f) to V_(6e) in which the sixth gear is in the in-gear state areregistered.

The gear position determiner 346 determines the gear positiondetermination value Da as “N−N” if the drum rotation angle signal Sa(voltage value Va) falls within none of the voltage ranges of theodd-stage in-gear information table 360 and the even-stage in-gearinformation table 362. The gear position determiner 346 determines thegear position determination value Da as “1−N” if the drum rotation anglesignal Sa (voltage value Va) falls within the first voltage range V_(1f)to V_(1e) and does not fall within the second voltage range V_(2f) toV_(2e), and as “1−2” if the drum rotation angle signal Sa (voltage valueVa) falls within the first voltage range V_(1f) to V_(1e) and the secondvoltage range V_(2f) to V_(2e).

This gear position determination value Da is supplied to a meter displayunit 364 set between the handles 42 of the saddle-ridden vehicle 10 anda character or numeral corresponding to the gear position determinationvalue Da is displayed in a predetermined display area of this meterdisplay unit 364. If the gear position determination value Da is “N−N,”representing neutral is displayed. If the gear position determinationvalue Da is “1−N” or “1−2,” the present shift stage is displayedaccording to the shift stage on a connected clutch side of two clutches.This applies also to the other gear position determination values Da.

The target gear position determiner 348 determines a target gearposition as the next gear position and outputs it as a target gearposition value Db based on the drum rotation angle signal Sa from thedrum rotation angle sensor 358, the gear position determination value Dafrom the gear position determiner 346, and a spindle rotation anglesignal Sb from a spindle rotation angle sensor 366 (see also FIG. 4)that detects the rotation angle of the shift spindle 290. As the spindlerotation angle signal Sb, e.g. a positive/negative voltage valueaccording to the operation direction and operation amount of the shiftpedal 48 can be employed. For example, a positive voltage value isoutput from the spindle rotation angle sensor 366 if the shift pedal 48is operated in a shift-up direction, and a negative voltage value isoutput from the spindle rotation angle sensor 366 if the shift pedal 48is operated in a shift-down direction. As the target gear position valueDb, the initial value (neutral state) is “0” and the valuescorresponding to the first, second, third, fourth, fifth, and sixth are“1,” “2,” “3,” “4,” “5,” and “6,” respectively.

The driving state determiner 350 determines the driving state of thesaddle-ridden vehicle 10, i.e. whether the saddle-ridden vehicle 10 isin the stop state or is about to start moving, based on an enginerotational speed signal ne from an engine rotational speed sensor 368that detects the rotational speed of the engine 36, a throttle openingsignal th from a throttle opening sensor 370 that detects the openingdegree of a throttle valve, and a vehicle velocity signal vr from avehicle velocity sensor 372 that detects the vehicle velocity of thesaddle-ridden vehicle 10. From this driving state determiner 350, asignal indicating a request for clutch disconnection in the stop state(stop-state clutch disconnection request signal Sc) is output.

The gear position determiner 346 determines whether the gear positiondetermination value Da indicates neutral (N−N). If it indicates neutral,display indicating the neutral state is output on the meter display unit364.

The connection clutch determiner 354 determines the clutch that shouldbe connected next, of the first clutch 264 a and the second clutch 264b, and outputs it as a connection clutch determination value Dc based onthe drum rotation angle signal Sa (voltage value Va) from the drumrotation angle sensor 358, the above-described odd-stage in-gearinformation table 360, the even-stage in-gear information table 362, thegear position determination value Da from the gear position determiner346, the target gear position value Db from the target gear positiondeterminer 348, the stop-state clutch disconnection request signal Scfrom the driving state determiner 350, and an operation signal Sd fromthe clutch-OFF switch 44. Of course, the connection clutch determiner354 also determines disconnection of both the first clutch 264 a and thesecond clutch 264 b.

As the connection clutch determination value Dc, for example “1” is usedin the case of connecting the first clutch 264 a, “2” is used in thecase of connecting the second clutch 264 b, and “0” is used in the caseof disconnecting both the first clutch 264 a and the second clutch 264b.

The first clutch capacity calculator 356A calculates capacity forconnecting/disconnecting the first clutch 264 a (first clutch capacityC1) and capacity for connecting/disconnecting the second clutch 264 b(second clutch capacity C2) based on the gear position determinationvalue Da from the gear position determiner 346, the target gear positionvalue Db from the target gear position determiner 348, the connectionclutch determination value Dc from the connection clutch determiner 354,and information necessary for automatic start and gear shift control(the engine rotational speed signal ne from the engine rotational speedsensor 368, the throttle opening signal th from the throttle openingsensor 370, the vehicle velocity signal vr from the vehicle velocitysensor 372, an engine torque determination value, and so forth). Thefirst clutch capacity C1 is supplied to the firstelectromagnetically-controlled valve 274 a as the first clutch capacityoutput value Sc1, and the second clutch capacity C2 is supplied to thesecond electromagnetically-controlled valve 274 b as the second clutchcapacity output value Sc2.

Processing operation of the first gearbox 200A will be described belowwith reference to flowcharts of FIGS. 18 to 20 and a timing chart ofFIG. 16.

First, in a step S1 of FIG. 18, the gear position determiner 346determines the present gear position and outputs it as the gear positiondetermination value Da based on the drum rotation angle signal Sa(voltage value Va) from the drum rotation angle sensor 358. Because thisstep has been described in detail, description of specific processing isomitted.

Next, in a step S2, the processing enters target gear positiondetermination by the target gear position determiner 348.

In this target gear position determination, first, in a step S101 inFIG. 19, it is determined whether or not the drum rotation angle signalSa (voltage value Va) from the drum rotation angle sensor 358 is equalto or larger than a permission threshold of shift-up gear change. Thisdetermination is made based on whether change in the drum rotation anglesignal Sa (voltage value Va) shows an increase direction (shift-upoperation direction) and the drum rotation angle signal Sa (voltagevalue Va) has become equal to or larger than a value corresponding tothe rotation angle of the shift drum 278 (voltage value) at the timingwhen the drum shifter 318 of the ratchet mechanism 288 returns to theoriginal position and the ratchet mechanism 288 is reset after the shiftdrum 278 rotates in association with shift-up operation of the shiftpedal 48 and the roller 314 of the stopper arm 308 moves beyond the topof the convex part of the shift drum center 298. For example, as shownin FIG. 16, in the case of shift-up from the first to the second, thedetermination is made based on whether the drum rotation angle signal Sa(voltage value Va) has become equal to or larger than the valuecorresponding to the rotation angle of the shift drum 278 (voltage valueV_(12U)) at the timing when the ratchet mechanism 288 is reset after theshift drum 278 rotates in association with shift-up operation of theshift pedal 48 and the roller 314 of the stopper arm 308 moves beyondthe top of the second convex part K₂ of the shift drum center 298.Similarly, in the case of shift-up from the second to the third, thedetermination is made based on whether the drum rotation angle signal Sa(voltage value Va) has become equal to or larger than the valuecorresponding to the rotation angle of the shift drum 278 (voltage valueV_(23U)) at the timing when the ratchet mechanism 288 is reset after theroller 314 of the stopper arm 308 moves beyond the top of the thirdconvex part K₃ of the shift drum center 298.

If it is determined in the above-described step S101 that the drumrotation angle signal Sa (voltage value Va) is equal to or larger thanthe permission threshold of shift-up gear change, the processingproceeds to the next step S102 and the target gear position value Db isincreased from the present target gear position value Db by one shiftstage. That is, the present target gear position value Db+1 is employedthis time as the target gear position value Db.

On the other hand, if it is determined in the above-described step S101that the drum rotation angle signal Sa (voltage value Va) is not equalto or larger than the permission threshold of shift-up gear change, theprocessing proceeds to the next step S103 and it is determined whetheror not the drum rotation angle signal Sa (voltage value Va) is equal toor smaller than a permission threshold of shift-down gear change. Thisdetermination is made based on whether change in the drum rotation anglesignal Sa (voltage value Va) shows a decrease direction (shift-downoperation direction) and the drum rotation angle signal Sa (voltagevalue Va) has become equal to or smaller than a value corresponding tothe rotation angle of the shift drum 278 (voltage value) at the timingwhen the drum shifter 318 of the ratchet mechanism 288 returns to theoriginal position and the ratchet mechanism 288 is reset after the shiftdrum 278 rotates in association with shift-down operation of the shiftpedal 48 and the roller 314 of the stopper arm 308 moves beyond the topof the convex part of the shift drum center 298. For example, as shownin FIG. 16, in the case of shift-down from the second to the first, thedetermination is made based on whether the drum rotation angle signal Sa(voltage value Va) has become equal to or smaller than the valuecorresponding to the rotation angle of the shift drum 278 (voltage valueV_(21D)) at the timing when the ratchet mechanism 288 is reset after theshift drum 278 rotates in the reverse direction in association withshift-down operation of the shift pedal 48 and the roller 314 of thestopper arm 308 moves beyond the top of the second convex part K₂ of theshift drum center 298.

If it is determined in the above-described step S103 that the drumrotation angle signal Sa (voltage value Va) is equal to or smaller thanthe permission threshold of shift-down gear change, the processingproceeds to the next step S104 and the target gear position value Db isdecreased from the present target gear position value Db by one shiftstage. That is, the present target gear position value Db−1 is employedthis time as the target gear position value Db.

If it is determined in the above-described step S103 that the drumrotation angle signal Sa (voltage value Va) is not equal to or smallerthan the permission threshold of shift-down gear change, the processingproceeds to the next step S105 and the target gear position value Db iskept at the present target gear position value Db.

Although the determination is made based on the drum rotation anglesignal Sa from the drum rotation angle sensor 358 in the above-describedstep S101 and step S103, the determination may be made based on thespindle rotation angle signal Sb from the spindle rotation angle sensor366. In this case, an operation amount of the shift pedal 48 in shiftfrom a certain shift stage to the next shift stage, particularly anoperation amount (voltage value) until the timing when the drum shifter318 of the ratchet mechanism 288 returns to the original position andthe ratchet mechanism 288 is reset after the roller 314 of the stopperarm 308 moves beyond the top of the convex part of the shift drum center298, is obtained in advance. At the timing when the spindle rotationangle signal Sb (voltage value) becomes the voltage value obtained inadvance, it may be determined that the spindle rotation angle signal Sbis equal to or larger than the permission threshold of shift-up gearchange or is equal to or smaller than the permission threshold ofshift-down gear change. The present shift stage cannot be detected withthe spindle rotation angle signal Sb alone. Therefore, a counter isadditionally set and a counter value is increased every shift-upoperation and decreased every shift-down operation. This allowsdetection of the shift stage from the counter value.

Of course, the determination may be made by using the drum rotationangle signal Sa and the spindle rotation angle signal Sb in combination.In this case, the calculation speed can be increased by determining theshift-down operation direction by the spindle rotation angle signal Sb.

Upon the end of the processing in the above-described step S102, stepS104, or step S105, the processing proceeds to a step S3 in FIG. 18 toenter connection clutch determination by the connection clutchdeterminer 354.

In this connection clutch determination, first, in a step S201 in FIG.20, whether or not the clutch-OFF switch 44 is operated is determined.If the clutch-OFF switch 44 is not operated, the processing proceeds tothe next step S202 and whether or not the target gear position value Dbis “0” is determined. If the target gear position value Db is not “0,”the processing proceeds to a step S203 and it is determined whether ornot the present state is the stop-state clutch disconnection state ofthe saddle-ridden vehicle 10. This determination is made based onwhether a stop-state clutch disconnection request is present. If thepresent state is not the stop-state clutch disconnection state of thesaddle-ridden vehicle 10, the processing proceeds to the next step S204and whether or not the gear position determination value Da is “N−N” isdetermined. If the gear position determination value Da is not “N−N,”the processing proceeds to the next step S205 and whether or not thegear of the odd stage side is in the in-gear state is determined withreference to the drum rotation angle signal Sa (voltage value Va) andthe voltage ranges registered in the odd-stage in-gear information table360. If the drum rotation angle signal Sa (voltage value Va) fallswithin the voltage range registered in the odd-stage in-gear informationtable 360, it is determined that the odd-stage gear is in the in-gearstate and the processing proceeds to the next step S206. In turn,whether or not the gear of the even stage side is in the in-gear stateis determined with reference to the drum rotation angle signal Sa(voltage value Va) and the voltage ranges registered in the even-stagein-gear information table 362. If the drum rotation angle signal Sa(voltage value Va) falls within the voltage range registered in theeven-stage in-gear information table 362, it is determined that theeven-stage gear is in the in-gear state and the processing proceeds tothe next step S207.

In the step S207, the value of the odd stage of the gear positiondetermination value Da is stored in an odd register and the value of theeven stage of the gear position determination value Da is stored in aneven register. Then, if |target gear position value−value of oddregister|>|target gear position value−value of even register| issatisfied, the processing proceeds to a step S208 and the connectionclutch determination value Dc is set to “2” indicating to connect thesecond clutch 264 b. Conversely, if |target gear position value−value ofodd register|>|target gear position value−value of even register| is notsatisfied, the processing proceeds to a step S209 and the connectionclutch determination value Dc is set to “1” indicating to connect thefirst clutch 264 a.

If it is determined in the above-described step S206 that the even-stagegear is not in the in-gear state, the processing proceeds to the stepS209 and the connection clutch determination value Dc is set to “1”indicating to connect the first clutch 264 a.

If it is determined in the above-described step S205 that the odd-stagegear is not in the in-gear state, the processing proceeds to a step S210and whether or not the even-stage gear is in the in-gear state isdetermined. If the even-stage gear is in the in-gear state, theprocessing proceeds to the above-described step S208 and the connectionclutch determination value Dc is set to “2” indicating to connect thesecond clutch 264 b.

On the other hand, if it is determined in the above-described step S201that the clutch-OFF switch 44 is operated, or if it is determined in thestep S202 that the target gear position value Db is “0,” or if it isdetermined in the step S203 that the present state is the stop-stateclutch disconnection state of the saddle-ridden vehicle 10, or if it isdetermined in the step S204 that the gear position determination valueDa is “N−N,” or if it is determined in the step S210 that the even-stagegear is not in the in-gear state, i.e. neither the odd-stage gear northe even-stage gear is in the in-gear state, the processing proceeds toa step S211 and the connection clutch determination value Dc is set to“0” indicating to disconnect both the first clutch 264 a and the secondclutch 264 b.

Upon the end of the processing in the above-described step S208, stepS209, or step S211, the processing proceeds to a step S4 in FIG. 18 toenter processing in the first clutch capacity calculator 356A.

In this processing in the first clutch capacity calculator 356A,calculation processing according to the connection clutch determinationvalue Dc from the connection clutch determiner 354 is executed.Specifically, if the connection clutch determination value Dc is “1,”the processing proceeds to a step S401 and clutch capacity (first clutchcapacity C1 and second clutch capacity C2) for connecting the firstclutch 264 a or for keeping the connected state of the first clutch 264a is calculated. The first clutch capacity C1 and the second clutchcapacity C2 are figured out by using various kinds of parameters (enginerotational speed, throttle opening, vehicle velocity, gear position,clutch input torque value, gear ratio, etc.) so that the optimum ridingfeeling may be obtained in every situation such as start, stop, anddriving of the saddle-ridden vehicle 10.

As shown in FIG. 5, the obtained first clutch capacity C1 is supplied tothe first electromagnetically-controlled valve 274 a of the hydraulicsupply system 268 as the first clutch capacity output value Sc1. Thefirst electromagnetically-controlled valve 274 a controls the hydraulicpressure supplied to the first clutch 264 a in such a direction as toconnect the first clutch 264 a or in order to keep the connected stateof the first clutch 264 a based on the supplied first clutch capacityoutput value Sc1. The second clutch capacity C2 is supplied to thesecond electromagnetically-controlled valve 274 b of the hydraulicsupply system 268 as the second clutch capacity output value Sc2. Thesecond electromagnetically-controlled valve 274 b controls the hydraulicpressure supplied to the second clutch 264 b in such a direction as todisconnect the second clutch 264 b or in order to keep the disconnectedstate of the second clutch 264 b based on the supplied second clutchcapacity output value Sc2. In particular, when the state is switchedfrom the connected state of the second clutch 264 b to the connectedstate of the first clutch 264 a, shift of the clutch is started.

If the connection clutch determination value Dc is “2,” the processingproceeds to a step S402 in FIG. 18 and clutch capacity (first clutchcapacity C1 and second clutch capacity C2) for connecting the secondclutch 264 b or for keeping the connected state of the second clutch 264b is calculated. The first clutch capacity C1 and the second clutchcapacity C2 are output to the first electromagnetically-controlled valve274 a and the second electromagnetically-controlled valve 274 b as thefirst clutch capacity output value Sc1 and the second clutch capacityoutput value Sc2.

The first electromagnetically-controlled valve 274 a controls thehydraulic pressure supplied to the first clutch 264 a in such adirection as to disconnect the first clutch 264 a or in order to keepthe disconnected state of the first clutch 264 a based on the suppliedfirst clutch capacity output value Sc1. The secondelectromagnetically-controlled valve 274 b controls the hydraulicpressure supplied to the second clutch 264 b in such a direction as toconnect the second clutch 264 b or in order to keep the connected stateof the second clutch 264 b based on the supplied second clutch capacityoutput value Sc2. In particular, when the state is switched from theconnected state of the first clutch 264 a to the connected state of thesecond clutch 264 b, shift of the clutch is started.

If the connection clutch determination value Dc is “0,” the processingproceeds to a step S403 in FIG. 18 and clutch capacity (first clutchcapacity C1 and second clutch capacity C2) for disconnecting both thefirst clutch 264 a and the second clutch 264 b or for keeping thedisconnected state of the first clutch 264 a and the second clutch 264 bis calculated. The first clutch capacity C1 and the second clutchcapacity C2 are output to the first electromagnetically-controlled valve274 a and the second electromagnetically-controlled valve 274 b as thefirst clutch capacity output value Sc1 and the second clutch capacityoutput value Sc2.

Here, operation of shift-up from the first to the second will bedescribed with reference also to timing charts of FIGS. 21 and 22. FIGS.21 and 22 are timing charts showing changes in the drum rotation anglesignal Sa (voltage value Va) associated with the operation position(operation amount) of the shift pedal 48, the gear positiondetermination value Da, the target gear position value Db, theconnection clutch determination value Dc, the first clutch capacityoutput value (Nm), the second clutch capacity output value (Nm), thevehicle velocity (km/h), and the engine rotational speed (r/m).

In FIG. 21, “1−N” of the drum rotation angle signal Sa (voltage valueVa) indicates the state in which the roller 314 of the stopper arm 308is located at the bottom of the first notch N₁ of the shift drum center298. “1−2” indicates the state in which the roller 314 of the stopperarm 308 is located at the top of the second convex part K₂. “N−2”indicates the state in which the roller 314 of the stopper arm 308 islocated at the bottom of the second notch N₂ of the shift drum center298.

First, at timing t1, operation of the shift pedal 48 to the shift-upside is started by the driver in driving in the first gear.

At timing t2, the shift drum 278 located at “1−N” starts to move toward“N−2” due to the operation of the shift pedal 48 to the shift-up side.

At timing t3, the gear position determination value Da derived from thedrum rotation angle signal Sa (voltage value Va) becomes “1−2.” At thistiming, gear shift to the second is not performed because it is unclearwhether the shift drum 278 will be settled to the position of “N−2”later. As shown by an arrow Ya in FIG. 16, the shift pedal 48 isreturned before the roller 314 of the stopper arm 308 moves beyond thetop of the second convex part K₂ in some cases. Thus, shift of theclutch is not started.

Next, at timing t4, specifically at the timing when the drum shifter 318of the ratchet mechanism 288 returns to the original position and theratchet mechanism 288 is reset after the roller 314 of the stopper arm308 moves beyond the second convex part K₂, i.e. at the timing when thedrum rotation angle signal Sa (voltage value Va) has become equal to orlarger than the permission threshold V_(12U) of shift-up gear change,the target gear position value Db is updated from “1” to “2.” Due tothis, the connection clutch determination value Dc is switched to “2,”which is the value causing connection of the second clutch 264 b, sothat gear shift (clutch shift) is started.

At the above-described timing t4, when the target gear position value Dbbecomes “2,” the gear position determination value Da is “1−2” andtherefore the connection clutch determination value Dc becomes “2.”Thus,the first clutch capacity output value Sc1 at an upper limit value thusfar changes in the decrease direction. Instead, the second clutchcapacity output value Sc2 at a lower limit value thus far changes in theincrease direction, so that shift of the clutch is carried out.

From the stage at which the shift pedal 48 reaches the stopper positionof the shift-up operation, the shift drum 278 continues to rotate due toinertia and the roller 314 of the stopper arm 308 relatively movestoward the bottom of the second notch N₂. At timing t5 in the process ofthis movement, the gear position determination value Da changes to “N−2”and the first clutch capacity output value Sc1 becomes the lower limitvalue.

Thereafter, at timing t6 when the roller 314 of the stopper arm 308 ispositioned at the bottom of the second notch N₂, gear shift operation tothe second is completed, and driving in the second gear is started.

If the shift pedal 48 starts to return to the neutral position after theabove-described timing t3 as shown at timing t7 in FIG. 22, the drumrotation angle signal Sa (voltage value Va) also starts to return toward“1−N.”

When the shift pedal 48 returns to the neutral position at subsequenttiming t8, the drum rotation angle signal Sa (voltage value Va) becomesa voltage value V₁N corresponding to “1−N” and gear shift operation tothe second is not carried out.

The above-described operation is the same also in shift-up from thesecond to the third, from the third to the fourth, from the fourth tothe fifth, and from the fifth to the sixth. Furthermore, the operationis the same also in shift-down from the sixth to the fifth, from thefifth to the fourth, from the fourth to the third, from the third to thesecond, and from the second to the first.

Here, gear shift operation by the shift pedal 48, mainly gear shiftoperation of sequential shift-up from the neutral state to the first,second, . . . and sixth, will be described with focus on the shift forks(first shift fork 280 a to fourth shift fork 280 d) and the cam grooves(first cam groove 282 a to fourth cam groove 282 d) with reference toFIGS. 4 and 23. FIG. 23 is a development view of the cam grooves.

First, at the start of the engine 36, the first shift fork 280 a to thefourth shift fork 280 d exist at shift positions in FIG. 23, i.e.positions of C/N−N and M/N−N, in the corresponding first cam groove 282a to fourth cam groove 282 d. Here, C denotes the countershaft 214 and Mdenotes the main shaft 212. The element in front of “−” denotes thestate of the odd stage and the element behind “−” denotes the state ofthe even stage. N indicates the neutral state, in which the respectivedogs of the shift stages are uncoupled from the corresponding dog holes.Therefore, C/N−N represents the shift position at which the dogs areuncoupled at both the odd stages and the even stages in the countershaft214, and M/N−N represents the shift position at which the dogs areuncoupled at both the odd stages and the even stages in the main shaft212.

In the first cam groove 282 a to the fourth cam groove 282 d, step partsby displacement to the left and right by each one stage are continuouslyformed on the basis of the position of N corresponding to the neutralstate. The respective sliding protrusions 286 are located to any of theleft stage, the center stage, and the right stage in the first camgroove 282 a to the fourth cam groove 282 d. Thereby, the correspondingslide gears are selectively moved to three places in the axialdirection.

When the engine 36 of the saddle-ridden vehicle is in the operatingstate and the saddle-ridden vehicle 10 is in the stop state, both thefirst clutch 264 a and the second clutch 264 b are kept at thedisconnected state. Then, the driver operates the shift pedal 48, whichcauses the first gearbox 200A to perform gear shift of the transmission232 from the neutral state to the first. From this state, the clutchsystem 204 is controlled to the connected state in association with therise of the engine rotational speed of the engine 36. Thereby, thesaddle-ridden vehicle 10 is started.

Specifically, the driver operates the shift pedal 48 and thereby theshift drum 278 rotates. Thereby, the first shift fork 280 a and thefourth shift fork 280 d move in the arrow direction along the first camgroove 282 a and the fourth cam groove 282 d corresponding to thecountershaft 214 side to reach C/1−N from C/N−N. The second shift fork280 b and the third shift fork 280 c move in the arrow direction alongthe second cam groove 282 b and the third cam groove 282 c correspondingto the main shaft 212 side to reach M/1−N.

Specifically, at C/1−N, the first shift fork 280 a is moved by one stagefrom the neutral position to the left end side of the shift drum 278,which moves the slide gear n5 to the side of the free gear n1.Meanwhile, the fourth shift fork 280 d remains at the neutral position.At M/1−N, both the second shift fork 280 b and the third shift fork 280c remain at the neutral position. Thereby, at C/1−N, the state in whichpower transmission by the first is possible is obtained. Specifically,on the odd stage side of the countershaft 214, the state in which thedog of the slide gear n5 is coupled to the dog hole of the free gear n1(gear n1 is in the in-gear state) is obtained. The even stage side is inthe dog-uncoupled state. That is, at C/1−N, the free gear n1 is fixed tothe countershaft 214 by the slide gear n5. Furthermore, only the firstclutch 264 a provided for the inner shaft 212 m is connected and theoutput from the crankshaft 54 is transmitted to the countershaft 214 viathe first gear by the inner shaft 212 m. Here, the in-gear state refersto the state in which the corresponding gear and the gear making a pairwith the corresponding gear can be driven by the corresponding gear, andthe dog-uncoupled state refers to the state in which coupling by the dogis absent and power is not transmitted between the gears making a pair.

When the driver operates the shift pedal 48 to rotate the shift drum 278in order to make shift-up to the second, at midway gear positions C/1−2and M/1−2, only the fourth shift fork 280 d moves by one stage to theright end side of the shift drum 278 along the fourth cam groove 282 d.Thereby, the slide gear n6 moves to the side of the free gear n2, whichprovides the state in which the dog of the slide gear n6 is coupled tothe dog hole of the free gear n2 (gear n2 is in the in-gear state) onthe even stage side of the countershaft 214. That is, at C/1−2 andM/1−2, the state is obtained in which the gear n1 is in the in-gearstate on the odd stage side of the countershaft 214 and the gear n2 isin the in-gear state on the even stage side. This stage is a preliminaryshift stage. Only the first clutch 264 a is connected whereas connectionof the second clutch 264 b is broken.

When the driver further operates the shift pedal 48 to rotate the shiftdrum 278, in the process of movement toward gear positions C/N−2 andM/N−2, the first shift fork 280 a moves to the neutral position andtransition to connection of the second clutch 264 b is made while theconnection of the first clutch 264 a is broken. Then, at the stage wherethe gear positions have become C/N−2 and M/N−2, the dog is uncoupled onthe odd stage side of the countershaft 214 and the gear n2 is in thein-gear state on the even stage side. That is, at C/N−2, the free gearn2 is fixed to the countershaft 214 by the slide gear n6. Furthermore,only the second clutch 264 b provided for the outer shaft 212 n isconnected and the output from the crankshaft 54 is transmitted to thecountershaft 214 via the second gear by the outer shaft 212 n.

Similarly, at gear positions C/3−2 and M/3−2, the gear n3 is in thein-gear state on the odd stage side of the countershaft 214 and the gearn2 is in the in-gear state on the even stage side. This stage is apreliminary shift stage. Only the second clutch 264 b is connectedwhereas connection of the first clutch 264 a is broken.

At gear positions C/3−N and M/3−N, the dog is uncoupled on the evenstage side of the countershaft 214 and the gear n3 is in the in-gearstate on the odd stage side. That is, the free gear n3 is fixed to thecountershaft 214 by the slide gear n5. Furthermore, only the firstclutch 264 a provided for the inner shaft 212 m is connected and theoutput from the crankshaft 54 is transmitted to the countershaft 214 viathe third gear by the inner shaft 212 m.

At gear positions C/3−4 and M/3−4, the gear n3 is in the in-gear stateon the odd stage side of the countershaft 214 and the gear n4 is in thein-gear state on the even stage side. This stage is a preliminary shiftstage. Only the first clutch 264 a is connected whereas connection ofthe second clutch 264 b is broken.

At gear positions C/N−4 and M/N−4, the dog is uncoupled on the odd stageside of the countershaft 214 and the gear n4 is in the in-gear state onthe even stage side. That is, the free gear n4 is fixed to thecountershaft 214 by the slide gear n6. Furthermore, only the secondclutch 264 b provided for the outer shaft 212 n is connected and theoutput from the crankshaft 54 is transmitted to the countershaft 214 viathe fourth gear by the outer shaft 212 n.

At a gear position C/5−4, the dog is uncoupled on the odd stage side ofthe countershaft 214 and the gear n4 is in the in-gear state on the evenstage side. At a gear position M/5−4, the gear m5 is in the in-gearstate on the odd stage side of the main shaft 212 and the dog isuncoupled on the even stage side. This stage is a preliminary shiftstage. Only the second clutch 264 b is connected whereas connection ofthe first clutch 264 a is broken.

At a gear position C/5−N, the dog is uncoupled on both the odd stageside and the even stage side of the countershaft 214. At a gear positionM/5−N, the gear m5 is in the in-gear state on the odd stage side of themain shaft 212 and the dog is uncoupled on the even stage side. That is,the free gear m5 engaged with the slide gear n5 of the countershaft 214is fixed to the inner shaft 212 m of the main shaft 212 by the slidegear m3. Furthermore, only the first clutch 264 a provided for the innershaft 212 m is connected and the output from the crankshaft 54 istransmitted to the countershaft 214 via the fifth gear by the innershaft 212 m.

At gear positions C/5−6 and M/5−6, the gear m5 is in the in-gear stateon the odd stage side of the main shaft 212 and the gear m6 is in thein-gear state on the even stage side. This stage is a preliminary shiftstage. Only the first clutch 264 a is connected whereas connection ofthe second clutch 264 b is broken.

At gear positions C/N−6 and M/N−6, the dog is uncoupled on the odd stageside of the main shaft 212 and the gear m6 is in the in-gear state onthe even stage side. That is, the free gear m6 engaged with the slidegear n6 of the countershaft 214 is fixed to the outer shaft 212 n of themain shaft 212 by the slide gear m4. Furthermore, only the second clutch264 b provided for the outer shaft 212 n is connected and the outputfrom the crankshaft 54 is transmitted to the countershaft 214 via thesixth gear by the outer shaft 212 n.

As above, in the first gearbox 200A, the gearshift system 208configuring the first gearbox 200A of the saddle-ridden vehicle 10 isprovided as a system driven by only manual operation (foot operation)based on shift pedal operation of the driver. Furthermore, the clutchsystem 204 is configured by the first clutch 264 a and the second clutch264 b assigned to the transmission gears of the odd stages and the evenstages and connection/disconnection of them is electronically controlledaccording to the shift position of the gearshift system 208. Thus, whileinterruption of driving force in the clutch system 204 can beeliminated, gear shift of the gearshift system 208 is made to depend ononly the manual operation of the driver and thereby the driver is keptfrom feeling delay in the time until gear shift completion. In addition,an electronic drive system (motor and so forth) of the gearshift system208 can be reduced and size reduction and weight reduction of the firstgearbox 200A can be achieved. That is, it becomes possible to performshift of the clutch (gear shift) in conjunction with gear interchangedirectly performed based on the shift-pedal operation of the driverwithout adding sensors and actuators to a conventional DCT (Dual-ClutchTransmission) vehicle. Thus, gear shift without delay against gear shiftintention of the driver can be performed. In addition, disconnection ofthe driving force at the time of the gear shift can be decreased and theshock can be rapidly reduced. Furthermore, switches necessary for ashift actuator and a full-automatic vehicle can also be abandoned, whichis advantageous also in reduction of the weight and cost.

A gear shift instruction by the driver is detected to carry outconnection/disconnection control of the first clutch 264 a and thesecond clutch 264 b based on a detection result of the drum rotationangle sensor 358 that detects the rotation angle of the shift drum 278of the gearshift system 208. Therefore, the connection/disconnectiontiming of the first clutch 264 a and the second clutch 264 b can bedetected by utilizing the drum rotation angle sensor 358. As a result,without adding another sensor to detect a gear shift instruction by thedriver, suppression of increase in the number of sensors andsimplification of the circuit configuration and algorithm of the ECU 230can be achieved.

The spindle rotation angle sensor 366 that detects the rotation angle ofthe shift spindle 290 is provided and a gear shift instruction by thedriver is detected to control the clutch system 204 based on a detectionresult of this spindle rotation angle sensor 366. Due to this feature, agear shift intention of the driver can be surely detected andenhancement of the gear shift accuracy can be achieved.

Connection/disconnection control of the clutch system 204 is started ifthe angle detected by the drum rotation angle sensor 358 surpasses theangle from a concave part of the notch to the next convex part andsurpasses a predetermined angle. Thus, it is recognized that gear shiftoperation is carried out and the clutch system 204 is controlled at thecompletion timing of the gear shift operation by the driver. Therefore,sure clutch control based on the gear shift operation can be carried outwith high accuracy.

The predetermined angle at which connection/disconnection control of theclutch system 204 is started is set between the angle at which theratchet mechanism 288 is reset and the angle at which the shift pedal 48reaches the stopper position. Thereby, connection/disconnection controlof the clutch system 204 is carried out in the state in which sure gearshift operation of the gearbox has been carried out. Thus, sure clutchcontrol can be carried out in association with gear shift operation.

Irrespective of whether the rotation of the shift drum 278 is forwardrotation or reverse rotation, the predetermined angle surpassing theangle to the next convex part is detected and connection/disconnectioncontrol of the clutch system 204 is started. Due to this feature, sureclutch control based on gear shift operation can be carried out withhigh accuracy in both shift-up and shift-down.

The predetermined angle is set to the same angle irrespective of whetherthe rotation of the shift drum 278 is forward rotation or reverserotation. Due to this feature, there is no difference in the starttiming of connection/disconnection of the clutch system 204 and thedriver is not given an uncomfortable feeling of connection/disconnectionof the clutch system 204 in shift-up or shift-down.

In general, if the transmission remains at gear positions in the in-gearstate at both the odd stage and the even stage, problems of frictionincrease, gear rattle at the time of the next gear shift, shockincrease, etc. occur. However, in the first gearbox 200A, even in manualoperation of the shift pedal 48, the position is restricted by the shiftdrum center 298 so that the transmission may be prevented from remainingat gear positions in the in-gear state at both the odd stage and theeven stage. Thus, the above-described problems do not occur.

If the previous-stage gear gets uncoupled when the shift pedal 48 isoperated to the stopper position, possibly the previous-stage gear getsuncoupled before shift of the clutch. However, in the first gearbox200A, even when the shift pedal 48 is operated to the stopper positionat the time of manual gear shift by operation of the shift pedal 48, thein-gear position can be kept at both the odd stage and the even stageand shift of the clutch can be surely performed.

If operation of the shift pedal 48 is uncertain (e.g. the roller 314 ofthe stopper arm 308 does not move beyond the convex part between pluralnotches and the shift pedal 48 is returned to the original position),gear shift (shift of the clutch) is not performed. This allows surergear shift (shift of the clutch).

By using the spindle rotation angle sensor 366 in combination with thedrum rotation angle sensor 358, the accuracy of sensing of gear feed bythe shift pedal is enhanced, which allows further surer gear shift(shift of the clutch).

Next, a gearbox according to a second embodiment (hereinafter, referredto as second gearbox 200B) will be described with reference to FIGS. 24to 33.

As shown in FIG. 24, this second gearbox 200B has almost the sameconfiguration as that of the above-described first gearbox 200A butdiffers in the following points.

Specifically, as shown in FIG. 24, the second gearbox 200B has a clutchlever 374 (including operation amount sensor: clutch operation element)instead of the clutch-OFF switch 44. As shown in FIG. 25, the ECU 230 ofthe second gearbox 200B has a clutch control mode determiner 376, amanual operation clutch capacity calculator 378, a manual operationclutch determiner 380, and a second clutch capacity calculator 356B inaddition to the gear position determiner 346, the target gear positiondeterminer 348, the driving state determiner 350, and the connectionclutch determiner 354 that are the same as those of the first gearbox200A.

The clutch control mode determiner 376 monitors the operation amount ofthe clutch lever 374. The clutch control mode determiner 376 determinesclutch operation as manual clutch operation at the timing when theoperation amount becomes equal to or larger than a predetermined amountand determines clutch operation as automatic clutch operation in othercases.

Specifically, an operation amount sensor 382 is connected to the clutchlever 374 and outputs a voltage value Vc according to the operationamount of the clutch lever 374. Specifically, as shown in FIG. 26, theoutput voltage value Vc of the operation amount sensor 382proportionally increases from the fully-grasped state of the clutchlever 374 toward the released state. An effective range of the outputvoltage value Vc is a range from an effective upper limit voltage valueVmax to an effective lower limit voltage value Vmin, defined byexcluding, from a dynamic range of the output voltage value Vc, avoltage range corresponding to a lever allowance and a voltage rangedefined in consideration of an abutting margin. Therefore, the clutchcontrol mode determiner 376 determines that manual clutch operation isstarted at the timing when the output voltage value Vc becomes equal toor smaller than the effective upper limit voltage value Vmax.

The manual operation clutch capacity calculator 378 calculates a manualoperation clutch capacity Cm based on the output voltage value Vc of theoperation amount sensor 382 (output voltage value in the effectiverange). Specifically, as shown in FIG. 26, the relationship between theoutput voltage value Vc of the operation amount sensor 382 and themanual operation clutch capacity Cm is as follows. Specifically, acapacity value corresponding to the effective lower limit voltage valueVmin is defined as 0 and a capacity value corresponding to the effectiveupper limit voltage value Vmax is defined as a maximum value Cmax, andthe capacity value Cm proportionally increases as the output voltagevalue Vc increases. That is, the manual operation clutch capacitycalculator 378 calculates the manual operation clutch capacity Cm basedon the output voltage value Vc of the operation amount sensor 382 andthe proportional relationship shown in FIG. 26.

The manual operation clutch determiner 380 determines the clutch thatshould be treated as the target of manual operation next, of the firstclutch 264 a and the second clutch 264 b, and outputs it as a manualoperation clutch determination value Dd based on the drum rotation anglesignal Sa (voltage value Va) from the drum rotation angle sensor 358,the above-described odd-stage in-gear information table 360, theeven-stage in-gear information table 362, the gear positiondetermination value Da from the gear position determiner 346, the targetgear position value Db from the target gear position determiner 348, andthe manual operation clutch capacity Cm from the manual operation clutchcapacity calculator 378. Also in this case, as the manual operationclutch determination value Dd, for example “1” is used in the case ofconnecting the first clutch 264 a and “2” is used in the case ofconnecting the second clutch 264 b.

If the determination result from the clutch control mode determiner 376indicates automatic clutch operation, the second clutch capacitycalculator 356B calculates the first clutch capacity C1 and the secondclutch capacity C2 by executing processing similar to that of the firstclutch capacity calculator 356A of the first gearbox 200A. That is, itcalculates clutch capacity under automatic control. If the determinationresult from the clutch control mode determiner 376 indicates manualclutch operation, the second clutch capacity calculator 356B calculatesa first clutch capacity C1 m and a second clutch capacity C2 m undermanual operation based on the first clutch capacity C1 and the secondclutch capacity C2 under automatic control and the manual operationclutch capacity Cm. The first clutch capacity C1 or C1 m is supplied tothe first electromagnetically-controlled valve 274 a as the first clutchcapacity output value Sc1 and the second clutch capacity C2 or C2 m issupplied to the second electromagnetically-controlled valve 274 b as thesecond clutch capacity output value Sc2.

Processing operation of the second gearbox 200B will be described belowwith reference to flowcharts of FIGS. 27 to 32 and a timing chart ofFIG. 33. FIG. 33 is a timing chart showing how the in-gear state of theodd-stage gears and the even-stage gears (to be described later), thegear position determination value Da, and the drum rotation angle signalSa (voltage value Va) from the drum rotation angle sensor 358 change inassociation with the rotation of the shift drum center 298.

First, in a step S501 in FIG. 27, the gear position determiner 346determines the present gear position based on the drum rotation anglesignal Sa (voltage value Va) from the drum rotation angle sensor 358 andoutputs it as the gear position determination value Da. This is based onthe same operation as that of the gear position determiner 346 of theabove-described first gearbox 200A and therefore description of specificprocessing is omitted.

Next, in a step S502, the processing enters target gear positiondetermination by the target gear position determiner 348.

In this target gear position determination, the target gear positiondeterminer 348 determines a target gear position as the next gearposition and outputs it as the target gear position value Db based onthe drum rotation angle signal Sa (voltage value Va), the gear positiondetermination value Da from the gear position determiner 346, and thespindle rotation angle signal Sb from the spindle rotation angle sensor366 that detects the rotation angle of the shift spindle 290. Thistarget gear position determination is also based on the same operationas that of the target gear position determiner 348 of theabove-described first gearbox 200A and therefore description of specificprocessing is omitted.

Next, in a step S503, it is determined whether clutch operation isautomatic clutch operation or manual clutch operation based on adetermination value from the clutch control mode determiner 376. Then,if the determination value is “0” indicating automatic clutch operation,the processing proceeds to the next step S504 to enter connection clutchdetermination by the connection clutch determiner 354.

In this connection clutch determination, first, in a step S601 in FIG.28, whether or not the target gear position value Db is “0” isdetermined. If the target gear position value Db is not “0,” theprocessing proceeds to a step S602 and it is determined whether or notthe present state is the stop-state clutch disconnection state of thesaddle-ridden vehicle 10. This determination is made based on whether astop-state clutch disconnection request is present. If the present stateis not the stop-state clutch disconnection state of the saddle-riddenvehicle 10, the processing proceeds to the next step S603 and whether ornot the gear position determination value Da is “N−N” is determined. Ifthe gear position determination value Da is not “N−N,” the processingproceeds to the next step S604 and whether or not the gear of the oddstage side is in the in-gear state is determined with reference to thedrum rotation angle signal Sa (voltage value Va) and the voltage rangesregistered in the odd-stage in-gear information table 360. If the drumrotation angle signal Sa (voltage value Va) falls within the voltagerange registered in the odd-stage in-gear information table 360, it isdetermined that the odd-stage gear is in the in-gear state and theprocessing proceeds to the next step S605. In turn, whether or not thegear of the even stage side is in the in-gear state is determined withreference to the drum rotation angle signal Sa (voltage value Va) andthe voltage ranges registered in the even-stage in-gear informationtable 362. If the drum rotation angle signal Sa (voltage value Va) fallswithin the voltage range registered in the even-stage in-gearinformation table 362, it is determined that the even-stage gear is inthe in-gear state and the processing proceeds to the next step S606.

In the step S606, the value of the odd stage of the gear positiondetermination value Da is stored in an odd register and the value of theeven stage of the gear position determination value Da is stored in aneven register. Then, if |target gear position value−value of oddregister|>|target gear position value−value of even register| issatisfied, the processing proceeds to a step S607 and the connectionclutch determination value Dc is set to “2” indicating to connect thesecond clutch 264 b. Conversely, if |target gear position value−value ofodd register|>|target gear position value−value of even register| is notsatisfied, the processing proceeds to a step S608 and the connectionclutch determination value Dc is set to “1” indicating to connect thefirst clutch 264 a.

If it is determined in the step S605 that the even-stage gear is not inthe in-gear state, the processing proceeds to the step S608 and theconnection clutch determination value Dc is set to “1” indicating toconnect the first clutch 264 a.

If it is determined in the above-described step S604 that the odd-stagegear is not in the in-gear state, the processing proceeds to a step S609and whether or not the even-stage gear is in the in-gear state isdetermined. If the even-stage gear is in the in-gear state, theprocessing proceeds to the above-described step S607 and the connectionclutch determination value Dc is set to “2” indicating to connect thesecond clutch 264 b.

On the other hand, if it is determined in the step S601 that the targetgear position value Db is “0,” or if it is determined in the step S602that the present state is the stop-state clutch disconnection state ofthe saddle-ridden vehicle 10, or if it is determined in the step S603that the gear position determination value Da is “N−N,” or if it isdetermined in the step S609 that the even-stage gear is not in thein-gear state, i.e. neither the odd-stage gear nor the even-stage gearis in the in-gear state, the processing proceeds to a step S610 and theconnection clutch determination value Dc is set to “0” indicating todisconnect both the first clutch 264 a and the second clutch 264 b.

If it is determined in the step S503 in FIG. 27 that clutch operation ismanual clutch operation, the processing proceeds to a step S505 to enterdetermination of the clutch as the manual operation target under manualoperation by the manual operation clutch determiner 380.

In this manual operation clutch determination, first, in a step S701 inFIG. 29, whether or not the odd-stage gear is in the in-gear state isdetermined. Because this determination method is described above,description thereof is omitted. If the odd-stage gear is not in thein-gear state, the processing proceeds to a step S702. In turn, whetheror not the even-stage gear is in the in-gear state is determined.Because this determination method is also described above, descriptionthereof is omitted. If it is determined that the even-stage gear is notin the in-gear state, i.e. neither the odd-stage gear nor the even-stagegear is in the in-gear state, the processing proceeds to the next stepS703 and the manual operation clutch determination value Dd is set to“1” indicating to treat the first clutch 264 a as the main target ofmanual operation.

If the even-stage gear is in the in-gear state in the above-describedstep S702, the processing proceeds to a step S704 and the manualoperation clutch determination value Dd is set to “2” indicating totreat the second clutch 264 b as the main target of manual operation.

If the odd-stage gear is in the in-gear state in the above-describedstep S701, the processing proceeds to a step S705 and, in turn, whetheror not the even-stage gear is in the in-gear state is determined.Because this determination method is also described above, descriptionthereof is omitted. If the even-stage gear is not in the in-gear state,the processing proceeds to a step S706 and the manual operation clutchdetermination value Dd is set to “1” indicating to treat the firstclutch 264 a as the main target of manual operation.

If it is determined in the above-described step S705 that the even-stagegear is in the in-gear state, the processing proceeds to a step S707. Inthis step, the value of the odd stage of the gear position determinationvalue Da is stored in an odd register and the value of the even stage ofthe gear position determination value Da is stored in an even register.Then, if |target gear position value−value of odd register|>|target gearposition value−value of even register| is satisfied, the processingproceeds to a step S708 and it is determined whether or not the manualoperation clutch determination value Dd indicates the even-stage clutch,i.e. “2.” If the even-stage clutch is not indicated, the processingproceeds to a step S709 and it is determined whether or not the manualoperation clutch capacity Cm is equal to or lower than the capacity ofclutch disconnection (clutch-OFF capacity). If the manual operationclutch capacity Cm surpasses the clutch-OFF capacity, the processingproceeds to a step S710 and it is determined whether or not the manualoperation clutch capacity Cm has changed in such a direction as toconnect the clutch. If the manual operation clutch capacity Cm has notchanged in such a direction as to connect the clutch, the processingproceeds to the next step S711 and the manual operation clutchdetermination value Dd is set to “1” indicating to treat the firstclutch 264 a as the main target of manual operation.

If it is determined in the above-described step S708 that the manualoperation clutch determination value Dd indicates the even-stage clutch,or if it is determined in the step S709 that the manual operation clutchcapacity Cm is equal to or lower than the clutch-OFF capacity, or if itis determined in the step S710 that the manual operation clutch capacityCm has changed in such a direction as to connect the clutch, theprocessing proceeds to a step S712 and the manual operation clutchdetermination value Dd is set to “2” indicating to treat the secondclutch 264 b as the main target of manual operation.

If it is determined in the above-described step S707 that |target gearposition value−value of odd register|>|target gear position value−valueof even register| is not satisfied, the processing proceeds to a stepS713 and it is determined whether or not the manual operation clutchdetermination value Dd indicates the odd-stage clutch, i.e. “1.” If theodd-stage clutch is not indicated, the processing proceeds to a stepS714 and it is determined whether or not the manual operation clutchcapacity Cm is equal to or lower than the clutch-OFF capacity. If themanual operation clutch capacity Cm surpasses the clutch-OFF capacity,the processing proceeds to a step S715 and it is determined whether ornot the manual operation clutch capacity Cm has changed in such adirection as to connect the clutch. If the manual operation clutchcapacity Cm has not changed in such a direction as to connect theclutch, the processing proceeds to the next step S716 and the manualoperation clutch determination value Dd is set to “2” indicating totreat the second clutch 264 b as the main target of manual operation.

If it is determined in the above-described step S713 that the manualoperation clutch determination value Dd indicates the odd-stage clutch,or if it is determined in the step S714 that the manual operation clutchcapacity Cm is equal to or lower than the clutch-OFF capacity, or if itis determined in the step S715 that the manual operation clutch capacityCm has changed in such a direction as to connect the clutch, theprocessing proceeds to the above-described step S706 and the manualoperation clutch determination value Dd is set to “1” indicating totreat the first clutch 264 a as the main target of manual operation.

Upon the end of the determination of the connection clutch underautomatic control by the connection clutch determiner 354 in the stepS504 in FIG. 27 or the determination of the clutch as the manualoperation target under manual operation by the manual operation clutchdeterminer 380 in the step S505, the processing proceeds to the nextstep S506 to enter processing in the second clutch capacity calculator356B.

In the processing in the second clutch capacity calculator 356B, first,in a step S801 in FIG. 30, whether or not clutch operation is automaticclutch operation (automatic mode) is determined based on a modedetermination value from the clutch control mode determiner 376. If themode determination value is “0” indicating automatic clutch operation,the processing proceeds to the next step S802 and calculation processingof the clutch capacity according to the connection clutch determinationvalue Dc from the connection clutch determiner 354 is executed as shownin the step S4 in FIG. 18. Specifically, if the connection clutchdetermination value Dc is “1,” the processing proceeds to a step S901and clutch capacity values for connecting the first clutch 264 a or forkeeping the connected state of the first clutch 264 a are calculated.That is, the clutch capacity of the first clutch 264 a under automaticcontrol (hereinafter, referred to as first automatic clutch capacityCa1) and the clutch capacity of the second clutch 264 b under automaticcontrol (hereinafter, referred to as second automatic clutch capacityCa2) are calculated. If the connection clutch determination value Dc is“2,” the processing proceeds to a step S902 and clutch capacity (firstautomatic clutch capacity Ca1 and second automatic clutch capacity Ca2)for connecting the second clutch 264 b or for keeping the connectedstate of the second clutch 264 b is calculated. If the connection clutchdetermination value Dc is “0,” the processing proceeds to a step S903and clutch capacity for disconnecting both the first clutch 264 a andthe second clutch 264 b or for keeping the disconnected state of thefirst clutch 264 a and the second clutch 264 b is calculated.

In a step S803, the first automatic clutch capacity Ca1 obtained by theprocessing of any of the steps S901 to S903 is set as the first clutchcapacity output value Sc1. In a step S804, the second automatic clutchcapacity Ca2 is set as the second clutch capacity output value Sc2. Theobtained first clutch capacity output value Sc1 and second clutchcapacity output value Sc2 are output to the firstelectromagnetically-controlled valve 274 a and the secondelectromagnetically-controlled valve 274 b.

If it is determined in the above-described step S801 that thedetermination value from the clutch control mode determiner 376indicates manual clutch operation (manual mode), the processing proceedsto the next step S805 and calculation processing of the clutch capacityaccording to the manual operation clutch determination value Dd from themanual operation clutch determiner 380 and manual operation is executed.

Specifically, in this calculation processing, if the manual operationclutch determination value Dd is “1,” the processing proceeds to a stepS904 and the clutch capacity is calculated with the first clutch 264 aregarded as the main target of manual operation. Specifically, in a stepS1001 in FIG. 31, it is determined whether or not the first clutchcapacity output value Sc1 has been shifted to the manual operationclutch capacity Cm. This determination is made based on whetherprocessing in a step S1005 and a step S1006 is executed via a step S1003to be described later. In this case, the determination may be made byusing flag information. For example, the following way is employed. Ifthe processing in the step S1005 and the step S1006 is executed for thefirst time with the same target gear position value Db, the flaginformation is set to “1” indicating that the output value Sc1 has beenshifted. At the timing when the clutch control mode has changed from themanual mode to the automatic mode or at the timing when the manualoperation clutch determination value Dd is switched, the flaginformation is reset to “0.” If the flag information is “1,” it isdetermined that the output value Sc1 has been shifted. If it is “0,” itis determined that the output value Sc1 has not been shifted.

If it is determined in the step S1001 that the output value Sc1 has notbeen shifted, the processing proceeds to a step S1002 and the clutchcapacity of the first clutch 264 a under automatic control in the manualmode (in-manual-mode first automatic clutch capacity Ca1) is calculated.In this step S1002, the calculation is so performed that the influenceon the vehicle body behavior is minimized also in view of the clutchcapacity of the second clutch 264 b under automatic control in themanual mode (in-manual-mode second automatic clutch capacity Ca2).

Thereafter, in the step S1003, the in-manual-mode first automatic clutchcapacity Ca1 is compared with the manual operation clutch capacity Cm.If in-manual-mode first automatic clutch capacity Ca1 ≧manual operationclutch capacity Cm is not satisfied, the processing proceeds to the nextstep S1004 and the in-manual-mode first automatic clutch capacity Ca1 isset as the first clutch capacity output value Sc1.

If it is determined in the above-described step S1003 thatin-manual-mode first automatic clutch capacity Ca1 ≧manual operationclutch capacity Cm is satisfied, the processing proceeds to the stepS1005 and the manual operation clutch capacity Cm is set as the firstclutch capacity output value Sc1. In the next step S1006, thein-manual-mode first automatic clutch capacity Ca1 is rewritten to themanual operation clutch capacity Cm.

Upon the end of the processing in the step S1004 or the processing inthe step S1006, the processing proceeds to a step S1007 and the clutchcapacity of the second clutch 264 b under automatic control in themanual mode (in-manual-mode second automatic clutch capacity Ca2) iscalculated. Also in this step S1007, the calculation is so performedthat the influence on the vehicle body behavior is minimized also inview of the in-manual-mode first automatic clutch capacity Ca1. Then, inthe next step S1008, the in-manual-mode second automatic clutch capacityCa2 is set as the second clutch capacity output value Sc2.

On the other hand, if the manual operation clutch determination value Ddis “2,” the processing proceeds to a step S905 in FIG. 30 and the clutchcapacity is calculated with the second clutch 264 b regarded as the maintarget of manual operation. Specifically, in a step S1101 in FIG. 32, itis determined whether or not the second clutch capacity output value Sc2has been shifted to the manual operation clutch capacity Cm. Thisdetermination is also made based on whether processing in a step S1105and a step S1106 is executed via a step S1103 to be described latersimilarly to the above-described step S1001.

If it is determined in the step S1101 that the output value Sc2 has notbeen shifted, the processing proceeds to a step S1102 and the clutchcapacity of the second clutch 264 b under automatic control in themanual operation (in-manual-mode second automatic clutch capacity Ca2)is calculated. In this step S1102, the calculation is so performed thatthe influence on the vehicle body behavior is minimized also in view ofthe in-manual-mode first automatic clutch capacity Ca1.

Thereafter, in the step S1103, the in-manual-mode second automaticclutch capacity Ca2 is compared with the manual operation clutchcapacity Cm. If in-manual-mode second automatic clutch capacityCa2≧manual operation clutch capacity Cm is not satisfied, the processingproceeds to the next step S1104 and the in-manual-mode second automaticclutch capacity Ca2 is set as the second clutch capacity output valueSc2.

If it is determined in the above-described step S1103 thatin-manual-mode second automatic clutch capacity Ca2 ≧manual operationclutch capacity Cm is satisfied, the processing proceeds to the stepS1105 and the manual operation clutch capacity Cm is set as the secondclutch capacity output value Sc2. In the next step S1106, thein-manual-mode second automatic clutch capacity Ca2 is rewritten to themanual operation clutch capacity Cm.

Upon the end of the processing in the step S1104 or the processing inthe step S1106, the processing proceeds to a step S1107 and thein-manual-mode first automatic clutch capacity Ca1 is calculated. Alsoin this step S1107, the calculation is so performed that the influenceon the vehicle body behavior is minimized also in view of thein-manual-mode second automatic clutch capacity Ca2. Then, in the nextstep S1108, the in-manual-mode first automatic clutch capacity Ca1 isset as the first clutch capacity output value Sc1.

Then, the first clutch capacity output value Sc1 and the second clutchcapacity output value Sc2 obtained through the step S1001 to the stepS1008 or the step S1101 to the step S1108 are output to the firstelectromagnetically-controlled valve 274 a and the secondelectromagnetically-controlled valve 274 b.

Here, operation of shift-up from the first to the second will bedescribed with reference also to a timing chart of FIG. 33. FIG. 33 is atiming chart showing changes in the drum rotation angle signal Sa(voltage value Va) associated with the operation position (operationamount) of the shift pedal 48, the gear position determination value Da,the target gear position value Db, the connection clutch determinationvalue Dc (manual operation clutch determination value Dd), the outputvoltage value (Vc) of the operation amount sensor 382 of the clutchlever 374, the first clutch capacity output value Sc1 (first automaticclutch capacity Ca1, manual operation clutch capacity Cm), and thesecond clutch capacity output value Sc2 (second automatic clutchcapacity Ca2, manual operation clutch capacity Cm).

First, at e.g. timing t11 in driving in the first gear, the clutch lever374 is not operated by the driver. Thus, based on the automatic controlmode, the first automatic clutch capacity Ca1 is output as the firstclutch capacity output value Sc1 and the second automatic clutchcapacity Ca2 is output as the second clutch capacity output value Sc2.

In the driving in the first gear, from timing t12 when the driveroperates the clutch lever 374 and the output voltage value Vc of theoperation amount sensor 382 becomes the effective upper limit voltagevalue Vmax, a manual operation mode Tw is started, so that the manualoperation clutch capacity Cm is output as the first clutch capacityoutput value Sc1 and the second automatic clutch capacity Ca2 is outputas the second clutch capacity output value Sc2. Thereby, the firstclutch 264 a is gradually disconnected according to the operation amountof the clutch lever 374. This state continues until the target gearposition value Db is changed, i.e. until the timing t4 when the drumshifter 318 of the ratchet mechanism 288 returns to the originalposition and the ratchet mechanism 288 is reset after the driveroperates the shift pedal 48 and the roller 314 of the stopper arm 308moves beyond the second convex part K₂ (timing when the drum rotationangle signal Sa (voltage value Va) becomes equal to or larger than thepermission threshold V_(12U) of shift-up gear change).

At the timing t4, the target gear position value Db is changed from “1”to “2.” Thus, from the timing t4, the manual operation clutch capacityCm is output as the second clutch capacity output value Sc2 and thefirst automatic clutch capacity Ca1 is output as the first clutchcapacity output value Sc1. Thereby, the second clutch 264 b is graduallyconnected according to the operation amount of the clutch lever 374.

Then, at timing t13 when the output voltage value Vc of the operationamount sensor 382 becomes the effective upper limit voltage value Vmax,the manual operation mode Tw ends and the automatic control mode isrestarted, so that the first automatic clutch capacity Ca1 is output asthe first clutch capacity output value Sc1 and the second automaticclutch capacity Ca2 is output as the second clutch capacity output valueSc2.

As above, in the second gearbox 200B, the same effects as those by theabove-described first gearbox 200A are achieved. In addition, controlreflecting driver's intention more is possible at the time of start/stopfor example, and the second gearbox 200B can be applied also to launchstart, wheelie, etc.

Transition between automatic clutch control and manual clutch controlcan be made without an uncomfortable feeling. Due to operation of theclutch lever 374, the clutch capacity is continuously switched at thetime of transition from automatic clutch control to manual clutchcontrol. Thus, switching without an uncomfortable feeling is possible.At the time of switching from manual clutch control to automatic clutchcontrol in the in-gear stop-state, unintentional movement of the vehiclecan be prevented.

Furthermore, the clutch lever 374 enabling connection/disconnectioncontrol of the clutch system 204 in accordance with driver's intentionis provided and the control device 230 receives an operation signal ofthis clutch lever 374 to output a clutch connection/disconnectioninstruction so that connection/disconnection control of the clutchsystem 204 can be carried out in accordance with driver's intentioninstead of automatic control by the control device 230. Therefore, theclutch system 204 allowing clutch operation from automatic clutchoperation to manual clutch operation can be configured through additionof the clutch lever 374 and small-scale change in the control device230. Thus, the saddle-ridden vehicle 10 permitting plural kinds ofoperation with the single vehicle can be provided at low cost.

An electronic switch measure is employed as the clutch lever 374.Therefore, the operation load can be reduced compared with conventionalmechanical switch measures. Thus, operation with a simple switch measureis allowed and reduction of the burden of driving operation can beachieved.

The gearbox of the saddle-ridden vehicle according to the presentinvention is not limited to the above-described embodiment and variousconfigurations can be employed without departing from the gist of thepresent invention.

DESCRIPTION OF REFERENCE SYMBOLS

-   10 . . . Saddle-ridden vehicle-   34 . . . Drive shaft-   36 . . . Engine-   44 . . . Clutch-OFF switch-   48 . . . Shift pedal-   54 . . . Crankshaft-   200A . . . First gearbox-   200B . . . Second gearbox-   202 . . . Primary reduction mechanism-   204 . . . Clutch system-   206 . . . Gear transmission mechanism-   208 . . . Gearshift system-   212 . . . Main shaft-   212 m . . . Inner shaft-   212 n . . . Outer shaft-   214 . . . Countershaft-   230 . . . ECU-   264 a . . . First clutch-   264 b . . . Second clutch-   268 . . . Hydraulic supply system-   270 . . . Clutch control device-   274 a . . . First electromagnetically-controlled valve-   274 b . . . Second electromagnetically-controlled valve-   278 . . . Shift drum-   280 a to 280 d . . . First shift fork to fourth shift fork-   282 a to 282 d . . . First cam groove to fourth cam groove-   288 . . . Ratchet mechanism-   290 . . . Shift spindle-   292 . . . Shift lever-   292 b . . . Tip part (change pedal shaft)-   294 . . . Shift rod-   296 . . . Shift arm-   298 . . . Shift drum center-   308 . . . Stopper arm-   314 . . . Roller-   318 . . . Drum shifter-   320 . . . Ratchet pawl-   322 . . . Spring-   334 . . . Engagement hole-   336 . . . Engagement pin-   338 . . . Arm-   340 . . . Elongate hole-   342 . . . Pin-   344 . . . Clamp spring-   344 a . . . Clamp arm-   346 . . . Gear position determiner-   348 . . . Target gear position determiner-   350 . . . Driving state determiner-   354 . . . Connection clutch determiner-   356 . . . Clutch capacity calculator-   358 . . . Drum rotation angle sensor-   366 . . . Spindle rotation angle sensor-   374 . . . Clutch lever-   376 . . . Clutch control mode determiner-   378 . . . Manual operation clutch capacity calculator-   380 . . . Manual operation clutch determiner-   382 . . . Operation amount sensor

The invention claimed is:
 1. A gearbox, comprising: a transmissionmechanism configured to be mounted on a saddle-ridden vehicle, whereindriving force generated by a power source is configured to be input tothe transmission mechanism, the transmission mechanism configured toperform gear shift by a plurality of transmission gears on power trainshafts divided for odd stages and even stages and to output the drivingforce; a clutch mechanism including a plurality of clutches configuredto allow mutually independent connection/disconnection operation and areeach assigned to a respective one of the power train shafts; a gearchange mechanism that is interlocked with a change pedal shaft to whichrotational force by operation of a shift pedal is configured to betransmitted and to arbitrarily select a transmission gear of thetransmission mechanism to perform gear shift; and a control deviceconfigured to electronically control connection/disconnection of theclutch mechanism according to a shift position of the gear changemechanism.
 2. The gearbox according to claim 1, the gear changemechanism comprising: a shift drum configured to be rotated by footoperation of a driver and to exclusively set one of the transmissiongears to a dog-in state to link the driving force, and a gear positionsensor configured to detect a rotation angle of the shift drum to detecta shift stage of the selected transmission gear, wherein the controldevice is configured to receive a gear shift instruction by the driverbased on a detection result of the gear position sensor and to carry outcontrol to connect/disconnect the plurality of clutches.
 3. The gearboxaccording to claim 2, the gear change mechanism further comprising: anintermittent feed mechanism configured to convert swing motion by theshift pedal to rotational motion of the shift drum, and a shift spindlerotation sensor located at a swing center of the intermittent feedmechanism and is configured to detect a rotation angle of aninterlocking shaft that interlocks the shift pedal with the shift drum,wherein the control device is configured to receive a gear shiftinstruction by the driver based on a detection result of the gearposition sensor and to carry out control to connect/disconnect theplurality of clutches.
 4. The gearbox according to claim 3, furthercomprising: a stopper retaining part disposed in the shift drum, thestopper retaining part having a circular disc shape and has concaveparts and convex parts alternately disposed at predetermined angles,wherein the gear change mechanism includes a stopper portion that isbiased against the stopper retaining part and is configured to stoprotation of the shift drum at a position at which the stopper portiongets into one of the concave parts to keep the shift drum at apredetermined shift stage, and wherein the control device is configuredto start connection/disconnection control of the clutch mechanism if anangle detected by the gear position sensor surpasses an angle from theconcave part to a top of a next convex part and further surpasses apredetermined angle.
 5. The gearbox according to claim 4, wherein theintermittent feed mechanism comprises a ratchet mechanism, and thepredetermined angle is set to an angle that is equal to or larger thanan angle at which the ratchet mechanism is reset and is equal to orsmaller than an angle at which the shift pedal reaches a stopperposition.
 6. The gearbox according to claim 4, wherein the controldevice is further configured to detect a predetermined angle surpassingan angle to a next convex part in both forward rotation and reverserotation of the shift drum to start connection/disconnection control ofthe clutch mechanism.
 7. The gearbox according to claim 6, wherein anangle at which the control device is configured to startconnection/disconnection of the clutch mechanism is set to the samepredetermined angle in both forward rotation and reverse rotation of theshift drum.
 8. The gearbox according to claim 1, wherein thesaddle-ridden vehicle includes a clutch operation element configured toallow the clutch mechanism to carry out connection/disconnection controlin accordance with intention of the driver, and the control device isconfigured to receive an operation signal from the clutch operationelement to output a clutch connection/disconnection instruction to theclutch mechanism.
 9. The gearbox according to claim 8, wherein theclutch operation element comprises an electronic system based on aswitch measure operable by a single finger.
 10. A gearbox, comprising:transmission means for being mounted on a saddle-ridden vehicle, and forhaving driving force generated by a power source input thereto, thetransmission means also for performing gear shift by a plurality oftransmission gears on power train shafts divided for odd stages and evenstages and for outputting the driving force; clutch means for allowingmutually independent connection/disconnection operation, said clutchmeans comprising a plurality of clutches, each assigned to a respectiveone of the power train shafts; gear change means interlocked with achange pedal shaft to which rotational force by operation of a shiftpedal is configured to be transmitted, said gear change means forarbitrarily selecting a transmission gear of the transmission means toperform gear shift; and control means for electronically controllingconnection/disconnection of the clutch means according to a shiftposition of the gear change means.
 11. The gearbox according to claim10, the gear change means comprising: shift drum means for being rotatedby foot operation of a driver and for exclusively setting one of thetransmission gears to a dog-in state to link the driving force, and gearposition sensor means for detecting a rotation angle of the shift drummeans and for detecting a shift stage of the selected transmission gear,wherein the control means is also for receiving a gear shift instructionby the driver based on a detection result of the gear position sensormeans and for carrying out control to connect/disconnect the pluralityof clutches.
 12. The gearbox according to claim 11, the gear changemeans further comprising: intermittent feed means for converting swingmotion by the shift pedal to rotational motion of the shift drum means,and shift spindle rotation sensor means located at a swing center of theintermittent feed means, for detecting a rotation angle of aninterlocking shaft that interlocks the shift pedal with the shift drummeans, wherein the control means is also for receiving a gear shiftinstruction by the driver based on a detection result of the gearposition sensor means and for carrying out control to connect/disconnectthe plurality of clutches.
 13. The gearbox according to claim 12,further comprising: stopper retaining means disposed in the shift drummeans, the stopper retaining means having a circular disc shape and hasconcave parts and convex parts alternately disposed at predeterminedangles, wherein the gear change mechanism includes a stopper means thatis biased against the stopper retaining means and is for stoppingrotation of the shift drum means at a position at which the stoppermeans gets into one of the concave parts to keep the shift drum means ata predetermined shift stage, and wherein the control means is also forstarting connection/disconnection control of the clutch means if anangle detected by the gear position sensor means surpasses an angle fromthe concave part to a top of a next convex part and further surpasses apredetermined angle.
 14. The gearbox according to claim 13, wherein theintermittent feed means comprises ratchet means, and the predeterminedangle is set to an angle that is equal to or larger than an angle atwhich the ratchet means is reset and is equal to or smaller than anangle at which the shift pedal reaches a stopper means position.
 15. Thegearbox according to claim 13, wherein the control means is also fordetecting a predetermined angle surpassing an angle to a next convexpart in both forward rotation and reverse rotation of the shift drummeans for starting connection/disconnection control of the clutch means.16. The gearbox according to claim 15, wherein an angle at which thecontrol means starts connection/disconnection of the clutch means is setto the same predetermined angle in both forward rotation and reverserotation of the shift drum means.
 17. The gearbox according to claim 10,wherein the saddle-ridden vehicle includes a clutch operation means forallowing the clutch means to carry out connection/disconnection controlin accordance with intention of the driver, and the control means isalso for receiving an operation signal from the clutch operation meansto output a clutch connection/disconnection instruction to the clutchmeans.
 18. The gearbox according to claim 17, wherein the clutchoperation means comprises an electronic system based on a switch measureoperable by a single finger.